Fermentation

23 pages, 2662 KB

Open AccessEditor’s ChoiceArticle

The Combined Effect of Four Nutraceutical-Based Feed Additives on the Rumen Microbiome, Methane Gas Emission, Volatile Fatty Acids, and Dry Matter Disappearance Using an In Vitro Batch Culture Technique

by Kelechi A. Ike, Deborah O. Okedoyin, Joel O. Alabi, Oludotun O. Adelusi, Michael Wuaku, Lydia K. Olagunju, Chika C. Anotaenwere, DeAndrea Gray, Peter A. Dele, Ahmed E. Kholif, Misty D. Thomas and Uchenna Y. Anele

Fermentation 2024, 10(10), 499; https://doi.org/10.3390/fermentation10100499 - 28 Sep 2024

Cited by 6 | Viewed by 2262

Abstract

This study aimed to investigate the effect of an essential oil/fumaric combination, mannan-oligosaccharide, galactooligosaccharide, and a mannan-oligosaccharide/galactooligosaccharide combination on the dry matter disappearance (DMD), gas production, greenhouse gasses, volatile fatty acid, and microbial community of a total mixed ration using a 24 [...] Read more.

This study aimed to investigate the effect of an essential oil/fumaric combination, mannan-oligosaccharide, galactooligosaccharide, and a mannan-oligosaccharide/galactooligosaccharide combination on the dry matter disappearance (DMD), gas production, greenhouse gasses, volatile fatty acid, and microbial community of a total mixed ration using a 24 h in vitro batch culture technique. The study design was a completely randomized design with four treatments as follows: a control treatment without any additives, the control treatment supplemented with galactooligosaccharide at 3% (Gos treatment), a galactooligosaccharide and mannan-oligosaccharide mixture at 1:1 at 3% (Gosmos treatment), or an essential oil blend (200 μL/g feed) and fumaric acid at 3% combination (Eofumaric treatment). The Gosmos treatment had the highest (p < 0.05) DMD (63.8%) and the numerical lowest acetate–propionate ratio (p = 0.207), which was 36.9% higher compared to the control. The lowest Shannon index, Simpson’s index, and all the diversity indices were recorded for the Eofumaric treatment, while the other treatments had similar Shannon index, Simpson’s index, and diversity index. The Z-score differential abundance between the Eofumaric and the control indicated that the inclusion of the Eofumaric treatment differentially increased the abundance of Patescibacteria, Synergistota, Chloroflexi, Actinobacteriota, Firmicutes, and Euryarchaeota while Verrucomicrobiota, WPS-2, Fibrobacterota, and Spirochaetota were decreased. The Random Forest Classification showed that the lower relative abundance of Fibrobacterota, Spirochaetota, and Elusimicrobiota and the higher relative abundance of Firmicutes and Chloroflexi were most impactful in explaining the microbial community data. Overall, the essential oil blend showed great potential as a methane gas mitigation strategy by modifying rumen fermentation through changes in the microbial community dynamics. Full article

(This article belongs to the Section Fermentation Process Design)

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11 pages, 2230 KB

Open AccessEditor’s ChoiceArticle

Neutral Red Film Augments Extracellular Electron Transfer Performed by Clostridium pasteurianum DSM 525

by Ana Clara Bonizol Zani, João Carlos de Souza, Adalgisa Rodrigues de Andrade and Valeria Reginatto

Fermentation 2024, 10(10), 497; https://doi.org/10.3390/fermentation10100497 - 27 Sep 2024

Cited by 7 | Viewed by 2422

Abstract

Extracellular electron transfer (EET) is key to the success of microbial fuel cells (MFCs). Clostridium sp. often occurs in MFC anode communities, but its ability to perform EET remains controversial. We have employed Clostridium pasteurianum DSM 525 as a biocatalyst in a glycerol-fed [...] Read more.

Extracellular electron transfer (EET) is key to the success of microbial fuel cells (MFCs). Clostridium sp. often occurs in MFC anode communities, but its ability to perform EET remains controversial. We have employed Clostridium pasteurianum DSM 525 as a biocatalyst in a glycerol-fed MFC, designated MFC_DSM. We have also followed the EET of this biocatalyst in the presence of a mediator, namely soluble neutral red (NR), soluble methyl viologen (MV), neutral red film (FNR), or methyl viologen film (FMV). MFC_DSM provided power and current densities (j) of 0.39 μW·cm⁻² and 2.47 μA·cm⁻², respectively, which evidenced that the biocatalyst performs direct electron transfer (DET). Introducing 150.0 µM NR or MV into the MFC_DSM improved the current density by 7.0- and 3.7-fold (17.05 and 8.45 μA·cm⁻²), respectively. After 20 cyclic voltammetry (CV) cycles, the presence of FNR in the MFC_DSM anodic chamber provided an almost twofold higher current density (30.76 µA·cm⁻²) compared to the presence of NR in the MFC_DSM. Introducing MV or FMV into the MFC_DSM anodic chamber gave practically the same current density after 10 CV cycles. The MFC_DSM anodic electrode might interact with FMV weakly than with FNR, so FNR is more promising to enhance C. pasteurianum DSM 525 EET within MFC_DSM. Full article

(This article belongs to the Special Issue Microbial Fuel Cell Advances)

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13 pages, 2228 KB

Open AccessEditor’s ChoiceArticle

Growth of Lactiplantibacillus plantarum BG112 in Batch and Continuous Culture with Camellia sinensis as Prebiotic

by Óscar Ariel Rojas-Rejón, Carlos Gonzalez-Figueredo, Ana Ruth Quintero-Covarrubias and Alejandro Saldaña-Jáuregui

Fermentation 2024, 10(9), 487; https://doi.org/10.3390/fermentation10090487 - 19 Sep 2024

Cited by 4 | Viewed by 6186

Abstract

This work aimed to study the effect of Camellia sinensis extract (CSExt) as a particular growth promoter of Lactiplantibacillus plantarum (LP) in batch and continuous production processes. Growth conditions were 1% (v/v) inoculum, pH_C = 6.5, 1% of [...] Read more.

This work aimed to study the effect of Camellia sinensis extract (CSExt) as a particular growth promoter of Lactiplantibacillus plantarum (LP) in batch and continuous production processes. Growth conditions were 1% (v/v) inoculum, pH_C = 6.5, 1% of dissolved oxygen (D.O.), 37 °C, and 150 rpm in a 0.2 L bioreactor using a commercial MRS broth (de Man, Rogosa, and Sharpe) and 1% (v/v) or 10% (v/v) CSExt according to the experimental design. In batch experiments, the maximum specific growth rate and the affinity constant increased with the increase in CSExt. In continuous culture, biomass production increased significantly with the addition of 1% (w/v) CSExt at 0.15 (1/h). Kinetic parameters adjusted were similar to those reported in the literature. Substrate affinity and the specific growth rate increased significantly in the presence of CSExt in batch and continuous cultures. Based on the results, prebiotics from plant extracts may function as growth promoters in specific physiological stages. This is the first report showing the change in kinetic parameters of a probiotic strain growing in crude plant extracts. Full article

(This article belongs to the Section Probiotic Strains and Fermentation)

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16 pages, 2634 KB

Open AccessEditor’s ChoiceArticle

A New Concept for the Rapid Development of Digital Twin Core Models for Bioprocesses in Various Reactor Designs

by André Moser, Christian Appl, Ralf Pörtner, Frank Baganz and Volker C. Hass

Fermentation 2024, 10(9), 463; https://doi.org/10.3390/fermentation10090463 - 6 Sep 2024

Cited by 13 | Viewed by 5772

Abstract

In this research work, a new software tool concept and its application for the rapid and flexible development of mechanistic digital twin core models for bioprocesses in various reactor designs are presented. The newly developed software tool concept automatically combines user-selected submodels into [...] Read more.

In this research work, a new software tool concept and its application for the rapid and flexible development of mechanistic digital twin core models for bioprocesses in various reactor designs are presented. The newly developed software tool concept automatically combines user-selected submodels into an overall digital twin core model. The main part is a biokinetic submodel, of which three were designed for enzymatic, microbial and biocatalytic processes, which can be adapted to specific processes. Furthermore, the digital twin core model contains a physico-chemical submodel (e.g., calculating pH or oxygen transfer) and a reactor submodel. The basis of the reactor submodel is an ideally mixed stirred tank reactor. The biokinetic submodel is decoupled from the reactor submodels and enables an independent parameterisation of submodels. Connecting ideally mixed stirred tank reactor models allows for the simulation of different reactor designs. The implementation of an executable digital twin core model was accelerated, creating a new software tool concept. When the concept was applied, the development time and the computing time of digital twin core models for the cultivation of Saccharomyces cerevisiae in two coupled stirred tank reactors as well as for enzymatic hydrolysis processes in a packed-bed reactor were reduced by 90%. Full article

(This article belongs to the Special Issue Fermentation Processes: Modeling, Optimization and Control: 2nd Edition)

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15 pages, 627 KB

Open AccessEditor’s ChoiceArticle

Effect of Skimmed Milk Powder and Fruit Jams Addition on the Physicochemical Characteristics of Yogurt

by Simona Janoušek Honesová, Eva Samková, Eva Dadáková, Lucie Hasoňová, Markéta Jarošová, Karolína Reindl and Jan Bárta

Fermentation 2024, 10(9), 462; https://doi.org/10.3390/fermentation10090462 - 5 Sep 2024

Cited by 3 | Viewed by 4715

Abstract

In three consecutive experiments, natural yogurt (NY) and fruit yogurt (FY) fortified with 5 and 10% skimmed milk powder (SMP) and 10% jam from black currant (BC), elderberry (EB), and their mixture of 1:1 (BCEB) were analyzed, and consumer acceptance was assessed. In [...] Read more.

In three consecutive experiments, natural yogurt (NY) and fruit yogurt (FY) fortified with 5 and 10% skimmed milk powder (SMP) and 10% jam from black currant (BC), elderberry (EB), and their mixture of 1:1 (BCEB) were analyzed, and consumer acceptance was assessed. In Experiment 1, the effect of SMP (0, 5, and 10%) on selected physicochemical parameters of the NY was evaluated. With the increasing addition of SMP, a decrease in fat content (up to −19%) and, conversely, an increase in protein content (up to +82%) and viscosity were noted. Analyses of fruits and jams intended for yogurt fortification revealed a significantly higher vitamin C content in BC than in EB and higher anthocyanins in EB than in BC. In Experiment 2, NY with 5 and 10% SMP was fortified with 10% jams (BC or EB). A joint effect of SMP and the type of fruit jam was evaluated. The same trends in fat and protein contents as in Experiment 1 were detected. The sensory evaluation showed better acceptance of FY with 10% SMP and no differences between BC and EB perception. Thus, for Experiment 3, FY was prepared with only 10% SMP and 10% jam (BC, EB, BCEB). Significant differences were detected in active acidity and color measured in the CIELab system. These results were also confirmed in sensory evaluation. The overall acceptability showed that FY with different types of jam did not significantly differ. The launching of innovative fortified yogurt onto the market represents a promising way to increase the diversity of fermented dairy products with nutritionally desirable properties. Full article

(This article belongs to the Special Issue Trends in the Development and Use of Fermented Dairy Products, 2nd Edition)

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11 pages, 484 KB

Open AccessEditor’s ChoiceArticle

Artisanal Cream Cheese Fermented with Kefir Grains

by Denise Rossi Freitas, Eliana Setsuko Kamimura and Mônica Roberta Mazalli

Fermentation 2024, 10(8), 420; https://doi.org/10.3390/fermentation10080420 - 13 Aug 2024

Cited by 7 | Viewed by 4914

Abstract

This is the first study that investigates the effect of kefir with an emphasis on the production of short-chain fatty acids (SCFAs) during the fermentation process in food products. The products developed and characterized were an artisanal cream cheese without cream and one [...] Read more.

This is the first study that investigates the effect of kefir with an emphasis on the production of short-chain fatty acids (SCFAs) during the fermentation process in food products. The products developed and characterized were an artisanal cream cheese without cream and one with added cream, and for the analysis of the fatty acid profile, both cream cheeses were compared with commercial cream cheese. The artisanal cream cheese had a high amount of lactic acid bacteria characterizing the product formed by Lactobacilli and a low concentration of lactose due to the fermentation process. Compared to commercial cream cheese, our products without and with added cream had a higher concentration of short-chain fatty acids (SCFAs), especially butyric acid, which is important for the health of the gastrointestinal tract, omega 3, and oleic fatty acid, which has been associated with the prevention and control of some diseases. Overall, the artisanal cream cheese cream with fermented cream with kefir grains is a functional product with an innovative character compared to current products on the market and was well accepted by the younger public. This new product comes as an option for those who need to change their eating habits and maintain a healthy lifestyle. Full article

(This article belongs to the Topic Fermented Food: Health and Benefit)

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17 pages, 2515 KB

Open AccessEditor’s ChoiceArticle

Thermal Treatment and Fermentation of Legume Flours with Leuconostoc citreum TR116 for the Development of Spreadable Meat Alternatives

by Aylin W. Sahin, Ophélie Gautheron and Sandra Galle

Fermentation 2024, 10(8), 412; https://doi.org/10.3390/fermentation10080412 - 9 Aug 2024

Cited by 7 | Viewed by 3656

Abstract

The demand for meat alternatives in different forms is increasing due to consumers’ awareness of climate change and the health benefits of plant-based ingredients compared to animals. However, current alternatives on the market do not fulfil consumers’ acceptance for taste and texture. Hence, [...] Read more.

The demand for meat alternatives in different forms is increasing due to consumers’ awareness of climate change and the health benefits of plant-based ingredients compared to animals. However, current alternatives on the market do not fulfil consumers’ acceptance for taste and texture. Hence, different physical and biological processes, such as thermal treatment and fermentation, need to be investigated. This study reveals that the thermal treatment of legume flours (soy, pea and lentil) prior to single-strain fermentation with Leuconostoc citreum TR116 has a major impact on acidification, colour, texture and sensory properties due to the pregelatinisation of starch and denaturation of proteins. The thermal treatment of soy flour resulted in liquification, and it could not be used as a fermentation substrate. However, non-heat-treated soy flour was fermented for comparison. The highest total titratable acidity (TTA) was determined in fermented pea flour (PF) and fermented lentil flour (LF) after 48 h with 24.35 ± 0.29 mL 0.1 M NaOH/10 g and 24.98 ± 0.33 mL 0.1 M NaOH/10 g, respectively. Heat treatment prior to fermentation led to a reduction in TTA by 20 mL 0.1 M NaOH/10 g for both PF and LF. The loss of colour pigments during thermal treatment led to a lighter colour of the spreadable alternatives. Moreover, a harder texture (+13.76 N in LF; +15.13 N in PF) and a lower adhesiveness (−0.88 N in LF; −0.43 N in PF) were detected in spreadable meat alternatives that were treated with heat prior to fermentation. Cohesiveness was decreased by thermal treatment, and fermentation did not impact it. Fermentation without pre-heat treatment increased adhesiveness by 4.37 N in LF and by 2.36 N in PF—an attribute typical for spreadable meat. Descriptive sensory analysis showed that thermal treatment significantly decreased bitterness but increased crumbliness and reduced juiciness. On the other hand, fermentation without pre-heat treatment mainly influenced flavour by increasing fruitiness and decreasing beaniness, earthiness and off-flavours. In summary, thermal treatment prior to fermentation is powerful in reducing legume-typical off-flavours but is not suitable for the development of spreadable meat alternatives due to texture changes. However, this process can be very beneficial when producing sausage-like alternatives. Full article

(This article belongs to the Special Issue Strategies for Optimal Fermentation by Using Modern Tools and Methods)

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19 pages, 1313 KB

Open AccessEditor’s ChoiceArticle

The Impact of Varying Levels of Laurus nobilis Leaves as a Sustainable Feed Additive on Ruminal Fermentation: In Vitro Gas Production, Methane and Carbon Dioxide Emissions, and Ruminal Degradability of a Conventional Diet for Ruminants

by Ahmed E. Kholif

Fermentation 2024, 10(8), 387; https://doi.org/10.3390/fermentation10080387 - 28 Jul 2024

Cited by 11 | Viewed by 2777

Abstract

The experiment aimed to evaluate the effects of varying levels of Laurus nobilis leaves [0% (control), 0.5%, 1%, 1.5%, and 2%] on the in vitro ruminal fermentation of a ruminant diet consisting of a 50% concentrate mixture, 40% berseem hay (Trifolium alexandrinum [...] Read more.

The experiment aimed to evaluate the effects of varying levels of Laurus nobilis leaves [0% (control), 0.5%, 1%, 1.5%, and 2%] on the in vitro ruminal fermentation of a ruminant diet consisting of a 50% concentrate mixture, 40% berseem hay (Trifolium alexandrinum), and 10% rice straw (Oryza sativa). The in vitro incubation lasted 48 h, during which gas production (GP), methane (CH₄), carbon dioxide (CO₂), total and individual short-chain fatty acids (SCFA), and nutrient degradability were measured. The experiment utilized a randomized block design and consisted of two incubation runs. Gas chromatography analysis revealed that 1,8-cineole (81%) was the primary volatile compound in the L. nobilis leaves. The 0.5% inclusion level exhibited the highest (linear, p = 0.006) asymptotic GP and lowest lag of GP (linear, p = 0.002), while the 2% inclusion level had the highest lag of GP. The 2% inclusion level significantly lowered CH₄ (linear, p = 0.003) compared to the control, and all levels of the leaves linearly decreased in the proportional CH₄ production (p = 0.001), with the lowest value at the 0.5% inclusion level. The highest asymptotic CO₂ production was observed with the 0.5% inclusion level (linear, p = 0.002), while the 0.5%, 1%, and 1.5% inclusion levels significantly increased (quadratic, p = 0.006) the proportion of CO₂ compared to the control. The 0.5% inclusion level showed the highest (p < 0.001) degradable DM and fiber fractions compared to the control, whereas the 2% level decreased them. The 0.5% inclusion level resulted in the highest (p < 0.01) production of total SCFA, acetate, and propionate. Additionally, the 0.5% inclusion level demonstrated the highest (p < 0.05) metabolizable energy and microbial crude protein, while the 2% level reduced these measures compared to the control. It is concluded that L. nobilis leaves can be included at 0.5% of the ruminant diet (e.g., sheep) to improve ruminal fermentation and reduce CH₄ production. Full article

(This article belongs to the Section Industrial Fermentation)

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18 pages, 2360 KB

Open AccessEditor’s ChoiceArticle

Black Tea Kombucha Consumption: Effect on Cardiometabolic Parameters and Diet Quality of Individuals with and without Obesity

by Gabriela Macedo Fraiz, Mirian A. C. Costa, Rodrigo R. Cardoso, James R. Hébert, Longgang Zhao, Viviana Corich, Alessio Giacomini, Fermín I. Milagro, Frederico A. R. Barros and Josefina Bressan

Fermentation 2024, 10(8), 384; https://doi.org/10.3390/fermentation10080384 - 26 Jul 2024

Cited by 12 | Viewed by 7091

Abstract

Background: Kombucha, a fermented tea, has been suggested as an adjuvant in the treatment of obesity. Although animal and in vitro studies indicate its promising benefits, exploring kombucha’s impact on human health is necessary. Methods: This quasi-experimental pre–post-intervention assessed the effect of black [...] Read more.

Background: Kombucha, a fermented tea, has been suggested as an adjuvant in the treatment of obesity. Although animal and in vitro studies indicate its promising benefits, exploring kombucha’s impact on human health is necessary. Methods: This quasi-experimental pre–post-intervention assessed the effect of black tea kombucha consumption on cardiometabolic parameters for 8 weeks, considering the quality of the diet of individuals with and without obesity. Diet quality was assessed through the Dietary Inflammatory Index^® and Dietary Total Antioxidant Capacity. Paired t-test/Wilcoxon was applied to compare differences between pre- and post-intervention (α = 0.05). Results: After the intervention, individuals with obesity showed a decrease in insulin, HOMA-IR, and GGT; those without obesity showed an increase in total cholesterol and alkaline phosphatase, but this was only observed in those with a worsened diet quality. Conclusion: kombucha intake demonstrated positive impacts on the metabolic health of individuals with obesity beyond the importance of combining it with healthy eating patterns. Full article

(This article belongs to the Special Issue Probiotics, Prebiotics and Their Use as Innovative Ingredients in Food Technology)

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16 pages, 5554 KB

Open AccessEditor’s ChoiceArticle

Optimizing Oxygen Exposure during Kombucha Brewing Using Air-Permeable Silicone Bags

by Briana Abigail R. Czarnecki, Kortnie M. Chamberlain, Ian M. Loscher, Emily R. Swartz, Lieke M. Black, Emma C. Oberholtzer, Jordan C. Scalia, Bret A. Watson, Lauren E. Shearer, John N. Richardson and Jeb S. Kegerreis

Fermentation 2024, 10(7), 371; https://doi.org/10.3390/fermentation10070371 - 20 Jul 2024

Cited by 4 | Viewed by 5733

Abstract

As the commercial and home brewing of kombucha expands to accommodate its increased popularity, novel brewing practices that generate non-alcoholic kombucha in an efficient manner become valuable. The research presented in this work compares kombucha brewed in a glass jar brewing vessel to [...] Read more.

As the commercial and home brewing of kombucha expands to accommodate its increased popularity, novel brewing practices that generate non-alcoholic kombucha in an efficient manner become valuable. The research presented in this work compares kombucha brewed in a glass jar brewing vessel to that brewed in an air-permeable silicone bag. Identical kombucha ferments with various sugar food sources were prepared and placed in each vessel, and variables such as titratable acidity, pH, alcohol by volume, gluconic acid concentration, acetic acid concentration, and sugar content were studied as a function of time. The results indicated that, regardless of the food source, kombucha brewed in an air-permeable bag exhibited more efficient acid production, lower ethanol concentration, and greater sugar utilization relative to equivalent kombucha brewed in a jar. Full article

(This article belongs to the Special Issue New Fermented Tea: Processing Technology, Microbiology and Health Benefits: 2nd Edition)

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17 pages, 2222 KB

Open AccessEditor’s ChoiceArticle

Phenotypic Characterization of Fermentation Performance and Stress Tolerance in Commercial Ale Yeast Strains

by Anqi Chen, Qiqi Si, Qingyun Xu, Chenwei Pan, Yuhan Cheng and Jian Chen

Fermentation 2024, 10(7), 364; https://doi.org/10.3390/fermentation10070364 - 18 Jul 2024

Cited by 2 | Viewed by 7270

Abstract

Yeast plays a crucial role in the fermentation industry, particularly in alcoholic beverage production, where robustness and metabolic flexibility are essential. This study aimed to investigate the stress tolerance and metabolic capabilities of seven commercial ale yeast strains under various stress conditions, including [...] Read more.

Yeast plays a crucial role in the fermentation industry, particularly in alcoholic beverage production, where robustness and metabolic flexibility are essential. This study aimed to investigate the stress tolerance and metabolic capabilities of seven commercial ale yeast strains under various stress conditions, including temperature, pH, osmotic pressure, glucose starvation, and ethanol concentration. Detailed growth assays and stress tolerance tests were utilized to evaluate fermentation efficiency, carbon source utilization, and stress adaptation. Significant variability was observed among the strains. ACY169 and ACY150 demonstrated high overall stress tolerance, making them suitable for high-gravity brewing and processes involving extreme temperature fluctuations. ACY10 showed robust performance under acid stress, making it ideal for sour beer production. In contrast, ACY5 exhibited limited adaptability under stress, with longer doubling times and reduced metabolic activity. The study also revealed differences in carbon source utilization, with ACY169 displaying exceptional metabolic versatility by efficiently fermenting various sugars, including glucose, fructose, maltose, and raffinose. ACY10 and ACY150 exhibited balanced fermentation profiles with high ethanol production rates, while ACY9 demonstrated the highest glucose consumption rate but lower ethanol yields and significant acidification. Full article

(This article belongs to the Special Issue Saccharomyces cerevisiae Strains and Fermentation: 2nd Edition)

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20 pages, 2733 KB

Open AccessEditor’s ChoiceArticle

A Semi-Continuous Fermentation Process for Pulque Production Using Microfiltration-Sterilized Aguamiel and Aseptic Conditions to Standardize the Overall Quality of the Beverage

by Concepción Calderón-García, Paula Cecilia Guadarrama-Mendoza, Edith Ponce-Alquicira, Adelfo Escalante, Yesica Ruiz-Ramírez and Rogelio Valadez-Blanco

Fermentation 2024, 10(7), 342; https://doi.org/10.3390/fermentation10070342 - 28 Jun 2024

Cited by 3 | Viewed by 5177

Abstract

Despite the current appreciation of pulque as a probiotic fermented beverage, pulque has been also regarded as a poor-quality product, particularly due to the lack of sanitary control during its elaboration. To address this problem, a semi-continuous fermentation system was established, emulating the [...] Read more.

Despite the current appreciation of pulque as a probiotic fermented beverage, pulque has been also regarded as a poor-quality product, particularly due to the lack of sanitary control during its elaboration. To address this problem, a semi-continuous fermentation system was established, emulating the artisanal production process. Microfiltration-sterilized aguamiel was employed as the substrate, whereas a good-quality pulque was used as the fermentation inoculum. During the fermentation, the physicochemical, microbiological (lactic acid and Leuconostoc-type bacteria and yeasts) and sensory characteristics of the must were monitored. The isolated microorganisms were identified by molecular biology and MALDI-MS techniques. The sterilization of aguamiel by microfiltration did not negatively affect its physicochemical attributes. After 6–8 days of operation of the semi-continuous bioreactor, the fermentation reached a quasi-stationary state considering most of the parameters monitored during the experiment. The final fermentation product presented similar physicochemical, microbial and sensory properties to those of the pulque inoculum. The genera identified were Leuconostoc, Lentilactobacillus, Lactobacillus, Liquorilactobacillus, Fructilactobacillus and Saccharomyces. The strains Lentilactobacillus diolivorans and Liquorilactobacillus capillatus and uvarum have not been previously isolated from pulque. In conclusion, the fermentation system developed in this work was effective to standardize the quality of pulque while preserving the positive attributes of the artisanal process, thus harnessing the probiotic properties of pulque. Full article

(This article belongs to the Section Fermentation for Food and Beverages)

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10 pages, 668 KB

Open AccessEditor’s ChoiceArticle

Evaluation of Essential Oils and Their Blends on the Fermentative Profile, Microbial Count, and Aerobic Stability of Sorghum Silage

by Elon S. Aniceto, Tadeu S. Oliveira, José R. Meirelles, Jr., Ismael N. Silva, Elvanio J. L. Mozelli Filho, Raphael S. Gomes, Juliana P. Arévalo and Patrícia R. Moraes

Fermentation 2024, 10(7), 335; https://doi.org/10.3390/fermentation10070335 - 27 Jun 2024

Cited by 4 | Viewed by 3491

Abstract

This study aims to evaluate the effect of these essential oils and their blends on the fermentative profile, losses by gases and effluents, nutritional value, microbial count, and aerobic stability of sorghum silage. A completely randomized design was used with eight treatments and [...] Read more.

This study aims to evaluate the effect of these essential oils and their blends on the fermentative profile, losses by gases and effluents, nutritional value, microbial count, and aerobic stability of sorghum silage. A completely randomized design was used with eight treatments and four repetitions. The evaluated treatments were the following: control (CON), without any essential oil; rosemary (Ros); tea tree (TT); citronella (Cit); Ros + TT (50% + 50%); Ros + Cit (50% + 50%); TT + Cit (50% + 50%); and Ros + TT + Cit (33% + 33% + 33%). A 1000 mg/kg dose of ensiled mass (as-fed basis) was used for each of the treatments. The addition of essential oils and their blends had a significant impact (p < 0.05) on the chemical composition of sorghum silage. Crude protein content increased (p < 0.001) with the use of essential oils and their blends. The Ros affected (p < 0.05) the fibrous fraction of sorghum silage. Neutral detergent fiber in vitro degradability was reduced (p = 0.003) when we used the blend TT + Cit compared to Ros and TT. We observed that only Ros did not reduce acetic acid concentration (p = 0.031) compared to the CON. The essential oils and their blends did not affect losses (p > 0.05). Lactic acid bacteria population increased (p = 0.039) when using the blend Ros + TT + Cit compared to the CON. However, the populations of entero-bacteria and fungi were not affected (p > 0.05) by the essential oils or their blends. For aerobic stability, we observed that Ros increased (p < 0.001) the air exposure time of the sorghum silage. Furthermore, the essential oils impacted the sorghum silage’s pH, which affected (p = 0.003) its aerobic stability. In conclusion, the essential oils did not reduce sorghum silage losses. However, the Ros improved the nutritional quality and aerobic stability of sorghum silage, while the blend Ros + TT + Cit increased the lactic acid bacteria count in the silage. More in-depth studies are needed to elucidate the action of essential oils as silage additives. Full article

(This article belongs to the Special Issue Application of Fermentation Technology in Animal Nutrition)

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19 pages, 3912 KB

Open AccessEditor’s ChoiceArticle

The Formulation of a Natural Detergent with a Biosurfactant Cultivated in a Low-Cost Medium for Use in Coastal Environmental Remediation

by Ivison A. da Silva, Fabíola Carolina G. de Almeida, Romulo N. Alves, Maristela C. C. Cunha, Jéssica Cristina M. de Oliveira, Mucio Luiz B. Fernandes and Leonie A. Sarubbo

Fermentation 2024, 10(7), 332; https://doi.org/10.3390/fermentation10070332 - 26 Jun 2024

Cited by 12 | Viewed by 7747

Abstract

Green surfactants have significant potential for improving environmental remediation methods. The aim of the present study was to formulate a green natural detergent containing the biosurfactant produced by Starmerella bombicola ATCC 22214 grown in 1.2% canola oil, 10% sucrose, and 0.5% corn steep [...] Read more.

Green surfactants have significant potential for improving environmental remediation methods. The aim of the present study was to formulate a green natural detergent containing the biosurfactant produced by Starmerella bombicola ATCC 22214 grown in 1.2% canola oil, 10% sucrose, and 0.5% corn steep liquor. The biosurfactant reduced surface tension to 31.84 mN/m and was produced at a yield of 22 g/L. Twelve formulations were proposed using cottonseed oil as the natural solvent and different stabilisers (vegetable wax, hydroxyethyl cellulose, and sodium alginate). The detergent was evaluated for its emulsifying capacity and stability over a 10-day period. Ecotoxicity was investigated using the marine recruitment test on metal plates covered with paint into which the biosurfactant was incorporated as well as tests with a microcrustacean and vegetable seeds. The formulation designated H, consisting of 1% biosurfactant, 40% cottonseed oil, and 2% hydroxyethyl cellulose, achieved the best results. The formulation exhibited both stability and emulsifying capacity (100% of petroleum). The ecotoxicity tests revealed the safety of the natural detergent. The detergent achieved satisfactory oil dispersion and solubilised 98% of the oil impregnated on the rock. The results indicate that the natural detergent holds promise for efficiently cleaning up environmental areas contaminated with oil and petroleum products. Full article

(This article belongs to the Special Issue Use of Agro-Industrial Waste and By-Products for the Sustainable Production of Eco-Friendly Surface-Active Compounds)

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12 pages, 1628 KB

Open AccessEditor’s ChoiceArticle

Antioxidant and Anticancer Potential of Extracellular Polysaccharide from Porphyridium aerugineum (Rhodophyta)

by Juliana G. Ivanova, Tanya S. Toshkova-Yotova, Reneta A. Toshkova, Veronika R. Deleva, Ani K. Georgieva and Liliana G. Gigova

Fermentation 2024, 10(5), 259; https://doi.org/10.3390/fermentation10050259 - 15 May 2024

Cited by 15 | Viewed by 4513

Abstract

Porphyridium aerugineum is a unicellular freshwater red microalga that synthesizes and secretes into the culture medium an extracellular polysaccharide (EPS). In this study, algal growth and polysaccharide production, as well as the antioxidant capacity and antitumor effect of Porphyridium aerugineum EPS (PaEPS), were [...] Read more.

Porphyridium aerugineum is a unicellular freshwater red microalga that synthesizes and secretes into the culture medium an extracellular polysaccharide (EPS). In this study, algal growth and polysaccharide production, as well as the antioxidant capacity and antitumor effect of Porphyridium aerugineum EPS (PaEPS), were investigated. Cultivation of the microalgae was carried out in a photobioreactor under controlled conditions. Algal growth and the amount of EPS were monitored daily. The accumulated polysaccharide was extracted and lyophilized. At the end of cultivation, the concentration of microalgal biomass and PaEPS reached 3.3 and 1.2 g L⁻¹, respectively. To examine the antioxidant capacity of PaEPS, FRAP and ABTS assays were performed. The cytotoxic activity of PaEPS was evaluated on the tumor cell lines MCF-7 (breast cancer) and HeLa (cervical adenocarcinoma) and on BJ (a non-tumor human skin fibroblast cell line), using MTT assay. The results obtained indicated that P. aerugineum polysaccharide exhibited a high ABTS radical-scavenging activity reaching up to 55%. The cytotoxic effect was best expressed in MCF-7 cells treated for 72 h with 1000 µg/mL PaEPS, where tumor cell proliferation was inhibited by more than 70%. Importantly, the PaEPS treatments did not significantly affect the viability of BJ cells. These findings promote the biotechnological production of P. aerugineum extracellular polysaccharide and reveal its potential as an anticancer and antioxidant agent for future applications. Full article

(This article belongs to the Special Issue Cyanobacteria and Eukaryotic Microalgae)

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15 pages, 831 KB

Open AccessEditor’s ChoiceArticle

Transcriptome Analysis of Sake Yeast in Co-Culture with kuratsuki Kocuria

by Karin Kobayashi and Hiromi Nishida

Fermentation 2024, 10(5), 249; https://doi.org/10.3390/fermentation10050249 - 10 May 2024

Cited by 3 | Viewed by 3124

Abstract

Kuratsuki bacteria enter the sake production process and affect the flavor and taste of sake. This study compared gene expression in the sake yeast Saccharomyces cerevisiae in co-culture with kuratsuki Kocuria to that in monoculture. Among the 5922 genes of S. cerevisiae, [...] Read more.

Kuratsuki bacteria enter the sake production process and affect the flavor and taste of sake. This study compared gene expression in the sake yeast Saccharomyces cerevisiae in co-culture with kuratsuki Kocuria to that in monoculture. Among the 5922 genes of S. cerevisiae, 71 genes were upregulated more than 2-fold, and 61 genes were downregulated less than 0.5-fold in co-culture with kuratsuki Kocuria. Among the stress-induced genes, fourteen were upregulated, and six were downregulated. Among the fourteen upregulated genes, six were induced in response to replication stress. Although the G1 cyclin gene CLN3 was upregulated by more than 2-fold, eight genes that were induced in response to meiosis and/or sporulation were also upregulated. Fourteen metabolism-related genes, for example, the glyceraldehyde-3-phosphate dehydrogenase genes TDH1, TDH2, and TDH3, were downregulated by less than 0.5-fold in co-culture with kuratsuki Kocuria. The gene expression patterns of S. cerevisiae co-cultured with kuratsuki Kocuria differed from those co-cultured with lactic acid bacteria. Therefore, S. cerevisiae responded differently to different bacterial species. This strongly suggests that kuratsuki bacteria affect gene expression in sake yeast, thereby affecting the flavor and taste of sake. Full article

(This article belongs to the Special Issue Applied and Fundamental Studies of Yeast in Fermented Foods and Beverages)

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24 pages, 2065 KB

Open AccessEditor’s ChoiceArticle

Autochthonous Ingredients for Craft Beer Production

by Vanesa Postigo, Luz Mauro, Teresa Diaz, Roberto Saiz, Teresa Arroyo and Margarita García

Fermentation 2024, 10(5), 225; https://doi.org/10.3390/fermentation10050225 - 24 Apr 2024

Cited by 8 | Viewed by 5416

Abstract

Innovation in the beer market focuses on research into the different ingredients that make up this popular and sought-after beverage. Some of these innovations have focused on the use of autochthonous ingredients, which bring added value to products, reduce production costs and environmental [...] Read more.

Innovation in the beer market focuses on research into the different ingredients that make up this popular and sought-after beverage. Some of these innovations have focused on the use of autochthonous ingredients, which bring added value to products, reduce production costs and environmental impact, and provide beers with special organoleptic characteristics. This study focuses on the use of autochthonous ingredients from the Community of Madrid and the design of four recipes that are suited to these ingredients and consumer demand. In terms of the ingredients used, the micromalting of barley grown in the CM was carried out, while hops (Cascade variety for bittering hops and wild hops Rayo verde Tajuña and Torreta Tajuña for aroma) and yeast strains (Saccharomyces cerevisiae G 520 and G 354) were selected from previous studies, which were also sourced from the CM. For the barley malt, parameters such as protein content were determined, which was at the maximum limit but did not affect the final quality of the beers. The content of α- and β-acids in the hops was also determined, being higher in the Cascade variety. Different physicochemical analyses (GC, aromatic compounds, bitterness, colour, SO₂, polyphenols, and antioxidant capacity) were carried out to determine the quality of the beers obtained from the four recipes designed, as well as tastings by a panel of experts and consumers. Finally, two recipes were rated the best by a panel of experts and consumers, where the cereal, hop, and fruit flavours stood out for their aromatic profile. Full article

(This article belongs to the Special Issue Advances in Beverages, Food, Yeast and Brewing Research, 3rd Edition)

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20 pages, 3098 KB

Open AccessEditor’s ChoiceArticle

Photoautotrophic Production of Docosahexaenoic Acid- and Eicosapentaenoic Acid-Enriched Biomass by Co-Culturing Golden-Brown and Green Microalgae

by Anna-Lena Thurn, Josef Schobel and Dirk Weuster-Botz

Fermentation 2024, 10(4), 220; https://doi.org/10.3390/fermentation10040220 - 18 Apr 2024

Cited by 15 | Viewed by 4365

Abstract

Marine microalgae offer a sustainable alternative source for the human diet’s essential omega-3-fatty acids, including docosahexaenoic acid (DHA, C22:6) and eicosapentaenoic acid (EPA, C20:5). However, none of them can produce DHA and EPA in a nutritionally balanced ratio of 1:1. As shown recently, [...] Read more.

Marine microalgae offer a sustainable alternative source for the human diet’s essential omega-3-fatty acids, including docosahexaenoic acid (DHA, C22:6) and eicosapentaenoic acid (EPA, C20:5). However, none of them can produce DHA and EPA in a nutritionally balanced ratio of 1:1. As shown recently, the phototrophic co-cultivation of the golden-brown microalgae Tisochrysis lutea (DHA producer) with the green microalgae Microchloropsis salina (EPA producer) can provide microalgae biomass with a balanced DHA-to-EPA ratio with increased productivity compared to monocultures. This study evaluates whether other golden-brown (Isochrysis galbana) and green microalgae (Nannochloropsis oceanica, Microchloropsis gaditana) can enable the phototrophic batch production of omega-3 fatty acids in a nutritionally balanced ratio in co-culture. All co-cultivations applying a physically dynamic climate simulation of a repeated sunny summer day in Australia in LED-illuminated flat-plate gas lift photobioreactors resulted in increased biomass concentrations compared to their respective monocultures, achieving balanced DHA-to-EPA ratios of almost 1:1. Using urea instead of nitrate as a nitrogen source increased the EPA content by up to 80% in all co-cultures. Light spectra measurements on the light-adverted side of the photobioreactor showed that increased biomass concentrations in co-cultures could have been related to enhanced light use due to the utilization of different wavelengths of the two microalgae strains, especially with the use of green light (500–580 nm) primarily by golden-brown microalgae (I. galbana) and orange light (600–620 nm) predominantly used by green microalgae (N. oceanica). Phototrophic co-cultivation processes thus promise higher areal biomass yields if microalgae are combined with complimentary light-harvesting features. Full article

(This article belongs to the Special Issue The Future of Fermentation Technology in the Biorefining Process: 2nd Edition)

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13 pages, 5694 KB

Open AccessEditor’s ChoiceArticle

Biohydrogen, Volatile Fatty Acids, and Biomethane from Mezcal Vinasses—A Dark Fermentation Process Evaluation

by Sergio A. Díaz-Barajas, Iván Moreno-Andrade, Edson B. Estrada-Arriaga, Liliana García-Sánchez and Marco A. Garzón-Zúñiga

Fermentation 2024, 10(4), 217; https://doi.org/10.3390/fermentation10040217 - 16 Apr 2024

Cited by 3 | Viewed by 3658

Abstract

Mezcal is a drink made in Mexico, the production of which generates vinasses with a high content of organic matter (OM) that is not utilized. However, these residues have the potential to be drawn upon in dark fermentation (DF) processes to obtain biogas [...] Read more.

Mezcal is a drink made in Mexico, the production of which generates vinasses with a high content of organic matter (OM) that is not utilized. However, these residues have the potential to be drawn upon in dark fermentation (DF) processes to obtain biogas rich in biohydrogen, biomethane, and volatile fatty acids (VFAs) with the potential to become biofuels. In the present work, the effect of reaction time (RT) and organic load (OL) was assessed based on the efficiency of removing OM, the production of VFAs, and the generation and composition of biogas in a process of DF fed with mezcal vinasses. The results show that increasing the RT and decreasing the OL increases COD removal but decreases biohydrogen production. The maximum production of H₂ (64 ± 21 NmL H₂/L_reactor) was obtained with the lowest RT (1 d) and the highest OL (13.5 gCODm³d⁻¹), while the highest accumulation of VFAs (2007 ± 327 mg VFA/L) was obtained with an RT of 3 d. It was determined that RT and OL are key parameters in DF processes for biohydrogen and VFA production. Full article

(This article belongs to the Special Issue Fermentative Biohydrogen Production)

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16 pages, 5217 KB

Open AccessEditor’s ChoiceArticle

Ethanol Production from a Mixture of Waste Tissue Paper and Food Waste through Saccharification and Mixed-Culture Fermentation

by Hongzhi Ma, Yueyao Wang, Pin Lv, Jun Zhou, Ming Gao, Dayi Qian, Bo Song and Qunhui Wang

Fermentation 2024, 10(4), 194; https://doi.org/10.3390/fermentation10040194 - 2 Apr 2024

Cited by 5 | Viewed by 5287

Abstract

This study focused on the co-fermentation of food waste and tissue paper to produce ethanol, which will eliminate the need for additional nitrogen sources and nutrients, thereby reducing production costs. In response to the inhibitory effect of the high concentrations of glucose present [...] Read more.

This study focused on the co-fermentation of food waste and tissue paper to produce ethanol, which will eliminate the need for additional nitrogen sources and nutrients, thereby reducing production costs. In response to the inhibitory effect of the high concentrations of glucose present in mixed-substrate hydrolysates on xylose fermentation, a co-fermentation process using Saccharomyces cerevisiae and Candida shehatae was proposed. This approach reduced the fermentation time by 24 h, increased the xylose utilization rate to 88%, and improved the ethanol yield from 41% to 46.5%. The impact of external conditions and corresponding optimization were also analyzed in this process. The optimum conditions were a 1:3 ratio of Saccharomyces cerevisiae to Candida shehatae, a pH of 5, and shaking at 150 r/min, and by employing dynamic temperature control, the ethanol production was increased to 21.98 g/L. Compared to conventional processes that only use Saccharomyces cerevisiae, this method enhanced the ethanol yield from 41% to 49%. Full article

(This article belongs to the Special Issue Anaerobic Digestion: Waste to Energy)

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17 pages, 1155 KB

Open AccessEditor’s ChoiceArticle

Sourdough Fermentation of Oat and Barley Flour with Bran and Its Application in Flatbread Made with No-Time and Dough Retardation Methods

by Tomislava Grgić, Saša Drakula, Bojana Voučko, Nikolina Čukelj Mustač and Dubravka Novotni

Fermentation 2024, 10(3), 174; https://doi.org/10.3390/fermentation10030174 - 21 Mar 2024

Cited by 8 | Viewed by 5979

Abstract

Dough retardation is commonly used to extend dough shelf-life, but it poses a challenge for flatbreads due to their large surface. This study explored the sourdough fermentation of oats and barley, addressing challenges in the retardation of dough for flatbread. Sourdough, using flour [...] Read more.

Dough retardation is commonly used to extend dough shelf-life, but it poses a challenge for flatbreads due to their large surface. This study explored the sourdough fermentation of oats and barley, addressing challenges in the retardation of dough for flatbread. Sourdough, using flour only or flour blended with bran (3:1), was fermented with a LIVENDO LV1 starter at 30 °C for 24 h. The pH value, microbial viable cell count, total titratable acidity and organic acids concentration of the sourdough were measured. The properties of dough and flatbread, depending on the retardation time (24 h and 48 h), sourdough type (oat or barley) and sourdough level (30% or 50% dough weight), were investigated. Oat flour’s limited acidification improved with the inclusion of bran, resulting in a desirable pH, TTA, and lactic to acetic acid ratio after 15 h of fermentation, which were comparable to results achieved with barley sourdough. The sourdough addition slowed down the enzymatic browning of dough during retardation. Dough retardation at 24 h reduced the phytates content (32–38%) and crumb hardness (9–16%), depending on the sourdough type and level. In dough retardation, β-glucans were degraded by up to 9% in the case of oats and by up to 28% in the samples with barley. Overall, adding oat or barley sourdough at a 30% dough weight can be recommended to enhance flatbread’s nutritional value and prolong its shelf life. Full article

(This article belongs to the Special Issue Nutrition and Health of Fermented Foods, 3rd Edition)

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13 pages, 801 KB

Open AccessEditor’s ChoiceArticle

Simultaneous Saccharification and Fermentation for Isobutanol Production from Banana Peel

by Hironaga Akita, Shodai Shibata, Tomoe Komoriya, Shinnosuke Kamei, Hiromichi Asamoto and Masakazu Matsumoto

Fermentation 2024, 10(3), 161; https://doi.org/10.3390/fermentation10030161 - 12 Mar 2024

Cited by 5 | Viewed by 5012

Abstract

Each year, near 40 million tons of banana peels are discarded around the world. This plant biomass could potentially be utilized for energy production. Simultaneous saccharification and fermentation (SSF) is an effective method for producing biofuels from plant biomasses. Since SSF with enzymatic [...] Read more.

Each year, near 40 million tons of banana peels are discarded around the world. This plant biomass could potentially be utilized for energy production. Simultaneous saccharification and fermentation (SSF) is an effective method for producing biofuels from plant biomasses. Since SSF with enzymatic hydrolysis and fermentation are performed simultaneously in the same reactor, the production process is simpler than most existing methods. Here, we describe isobutanol production using SSF with hydrothermally treated banana peel samples and an Escherichia coli strain able to utilize glucose and xylose to produce isobutanol. To enhance the glucose and xylose concentrations, the reaction conditions for the enzymatic hydrolysis of plant biomass using two kinds of saccharification enzymes were optimized, including the enzyme unit ratio, reaction temperature and sample gram. When the optimized conditions for enzymatic hydrolysis were applied to SSF, the glucose and xylose produced from the hydrothermally treated samples were consumed, producing isobutanol. Moreover, the isobutanol concentration increased with an increasing initial culture pH, reaching 1.27 g/L at pH 6.5, which was consistent with the optimal initial culture pH for isobutanol production by this E. coli strain. Taken together, these results indicate that the established method is potentially useful for industrial isobutanol production. Full article

(This article belongs to the Special Issue Bioconversion of Biomass for Effective Production of Biofuels as Well as Biobased Chemicals and Materials)

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12 pages, 1376 KB

Open AccessEditor’s ChoiceArticle

ADM1-Based Modeling of Biohydrogen Production through Anaerobic Co-Digestion of Agro-Industrial Wastes in a Continuous-Flow Stirred-Tank Reactor System

by Christina N. Economou, Georgios Manthos, Dimitris Zagklis and Michael Kornaros

Fermentation 2024, 10(3), 138; https://doi.org/10.3390/fermentation10030138 - 29 Feb 2024

Cited by 10 | Viewed by 4863

Abstract

Biological treatment is a promising alternative for waste management considering the environmentally sustainable concept that the European Union demands. In this direction, anaerobic digestion comprises a viable waste treatment process, producing high energy-carrier gases such as biomethane and biohydrogen under certain operating conditions. [...] Read more.

Biological treatment is a promising alternative for waste management considering the environmentally sustainable concept that the European Union demands. In this direction, anaerobic digestion comprises a viable waste treatment process, producing high energy-carrier gases such as biomethane and biohydrogen under certain operating conditions. The mathematical modeling of this bioprocess can be used as a valuable tool for process scale-up with cost-effective implications. The scope of this work was the evaluation of the well-established Anaerobic Digestion Model 1 (ADM1) for use in two-stage anaerobic digestion of agro-industrial waste. Certain equations for the description of the metabolic pathways for lactate and bioethanol accumulation were implemented in the existing mechanistic model in order to enhance the model’s accuracy. The model presents a high estimation ability regarding the final product (H₂ and biogas) reaching the same maximum value for the theoretical as the experimental data of these products (0.0012 and 0.0036 m³/d, respectively). The adapted ADM1 emerges as a useful instrument for designing anaerobic co-digestion processes with the goal of achieving high yields in fermentative hydrogen production, considering mixed biomass growth mechanisms. Full article

(This article belongs to the Special Issue Biological Conversion of Biomass Residues and Waste Streams for the Sustainable Production of Biofuels and Bio-Based Products: 2nd Edition)

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17 pages, 2920 KB

Open AccessEditor’s ChoiceArticle

Biogas Upgrading by Wild Alkaliphilic Microalgae and the Application Potential of Their Biomass in the Carbon Capture and Utilization Technology

by Yuri Kikuchi, Daichi Kanai, Kenjiro Sugiyama and Katsuhiko Fujii

Fermentation 2024, 10(3), 134; https://doi.org/10.3390/fermentation10030134 - 28 Feb 2024

Cited by 10 | Viewed by 4488

Abstract

Although biogas is a renewable energy source alternative to natural gas, it contains approximately 40 vol% CO₂ and, hence, a low calorific value. The sequestration of CO₂ from biogas is, therefore, essential before its widespread use. As CO₂ can be [...] Read more.

Although biogas is a renewable energy source alternative to natural gas, it contains approximately 40 vol% CO₂ and, hence, a low calorific value. The sequestration of CO₂ from biogas is, therefore, essential before its widespread use. As CO₂ can be easily solubilized as carbonate and bicarbonate in alkaline water, in this study, we isolated and characterized alkaliphilic wild microalgae that grow under high-level CO₂ conditions and evaluated their application potential in CO₂-removal from biogas. For this purpose, freshwater samples were enriched with 10 vol% CO₂ and an alkaline culture medium (pH 9.0), wherein almost free CO₂ was converted to carbonate and bicarbonate to yield alkaliphilic and high-level CO₂-tolerant microalgae. Ten microalgal strains of Micractinium, Chlorella, Scenedesmus/Tetradesmus, or Desmodesmus spp. were isolated, some of which demonstrated good growth even under conditions of >pH 10 and >30 vol% CO₂. All algal strains grew well through fixing biogas-derived CO₂ in a vial-scale biogas upgrading experiment, which reduced the CO₂ level in biogas to an undetectable level. These strains yielded antioxidant carotenoids, including lutein, astaxanthin, zeaxanthin, and β-carotene, particularly rich in lutein (up to 7.3 mg/g dry cells). In addition, these strains contained essential amino acids, accounting for 42.9 mol% of the total amino acids on average, and they were rich in unsaturated fatty acids (comprising 62.2 wt% of total fatty acids). The present study identified strains that can contribute to biogas upgrading technology, and the present findings suggest that their biomass can serve as useful raw material across the food, nutraceutical, and feed industries. Full article

(This article belongs to the Special Issue Microbial Culture and Isolation for the Production of Biofuels)

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12 pages, 2159 KB

Open AccessEditor’s ChoiceArticle

Differences in the Volatile Profile of Apple Cider Fermented with Schizosaccharomyces pombe and Schizosaccharomyces japonicus

by Nicola Ferremi Leali, Elisa Salvetti, Giovanni Luzzini, Andrea Salini, Davide Slaghenaufi, Salvatore Fusco, Maurizio Ugliano, Sandra Torriani and Renato L. Binati

Fermentation 2024, 10(3), 128; https://doi.org/10.3390/fermentation10030128 - 25 Feb 2024

Cited by 15 | Viewed by 4336

Abstract

In this study, two strains of Schizosaccharomyces pombe (NCAIM Y01474^T and SBPS) and two strains of Schizosaccharomyces japonicus (DBVPG 6274^T, M23B) were investigated for their capacity to ferment apple juice and influence the volatile compounds of cider compared to Saccharomyces [...] Read more.

In this study, two strains of Schizosaccharomyces pombe (NCAIM Y01474^T and SBPS) and two strains of Schizosaccharomyces japonicus (DBVPG 6274^T, M23B) were investigated for their capacity to ferment apple juice and influence the volatile compounds of cider compared to Saccharomyces cerevisiae EC1118. The ethanol tolerance and deacidification capacity of Schizosaccharomyces yeasts could make them potential substitutes for the commonly used S. cerevisiae starter cultures. Despite different time courses (10–30 d), all strains could complete the fermentation process, and Schizosaccharomyces strains reduced the concentration of malic acid in the apple juice. Results indicated that each yeast exerted a distinctive impact on the volatile profile of the apple cider, giving final products separated using a principal component analysis. The volatile composition of the cider exhibited significant differences in the concentration of alcohols, esters, and fatty acids. Particularly, the flocculant strain S. japonicus M23B increased the levels of ethyl acetate (315.44 ± 73.07 mg/L), isoamyl acetate (5.99 ± 0.13 mg/L), and isoamyl alcohol (24.77 ± 15.19 mg/L), while DBVPG 6274^T incremented the levels of phenyl ethyl alcohol and methionol up to 6.19 ± 0.51 mg/L and 3.72 ± 0.71 mg/L, respectively. A large production of terpenes and ethyl esters (e.g., ethyl octanoate) was detected in the cider fermented by S. cerevisiae EC1118. This study demonstrates, for the first time, the possible application of S. japonicus in cider-making to provide products with distinctive aromatic notes”. Full article

(This article belongs to the Special Issue Advances in Beverages, Food, Yeast and Brewing Research, 3rd Edition)

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14 pages, 1449 KB

Open AccessEditor’s ChoiceArticle

The Potential Use of Pseudomonas stutzeri as a Biocatalyst for the Removal of Heavy Metals and the Generation of Bioelectricity

by Rojas-Flores Segundo, Magaly De La Cruz-Noriega, Luis Cabanillas-Chirinos, Nélida Milly Otiniano, Nancy Soto-Deza, Walter Rojas-Villacorta and Mayra De La Cruz-Cerquin

Fermentation 2024, 10(2), 113; https://doi.org/10.3390/fermentation10020113 - 19 Feb 2024

Cited by 11 | Viewed by 5034

Abstract

Currently, industry in all its forms is vital for the human population because it provides the services and goods necessary to live. However, this process also pollutes soils and rivers. This research provides an environmentally friendly solution for the generation of electrical energy [...] Read more.

Currently, industry in all its forms is vital for the human population because it provides the services and goods necessary to live. However, this process also pollutes soils and rivers. This research provides an environmentally friendly solution for the generation of electrical energy and the bioremediation of heavy metals such as arsenic, iron, and copper present in river waters used to irrigate farmers’ crops. This research used single-chamber microbial fuel cells with activated carbon and zinc electrodes as anodes and cathodes, respectively, and farmers’ irrigation water contaminated with mining waste as substrate. Pseudomonas stutzeri was used as a biocatalyst due to its ability to proliferate at temperatures between 4 and 44 °C—at which the waters that feed irrigated rivers pass on their way to the sea—managing to generate peaks of electric current and voltage of 4.35 mA and 0.91 V on the sixth day, which operated with an electrical conductivity of 222 mS/cm and a pH of 6.74. Likewise, the parameters of nitrogen, total organic carbon, carbon lost on the ignition, dissolved organic carbon, and chemical oxygen demand were reduced by 51.19%, 79.92%, 64.95%, 79.89%, 79.93%, and 86.46%. At the same time, iron, copper, and arsenic values decreased by 84.625, 14.533, and 90.831%, respectively. The internal resistance values shown were 26.355 ± 4.528 Ω with a power density of 422.054 mW/cm² with a current density of 5.766 A/cm². This research gives society, governments, and private companies an economical and easily scalable prototype capable of simultaneously generating electrical energy and removing heavy metals. Full article

(This article belongs to the Special Issue Recent Advances in Bioconversion of Biomass to Value-Added Products)

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13 pages, 278 KB

Open AccessEditor’s ChoiceArticle

Synergistic Effects of Essential Oil Blends and Fumaric Acid on Ruminal Fermentation, Volatile Fatty Acid Production and Greenhouse Gas Emissions Using the Rumen Simulation Technique (RUSITEC)

by Joel O. Alabi, Peter A. Dele, Deborah O. Okedoyin, Michael Wuaku, Chika C. Anotaenwere, Oludotun O. Adelusi, DeAndrea Gray, Kelechi A. Ike, Olatunde A. Oderinwale, Kiran Subedi and Uchenna Y. Anele

Fermentation 2024, 10(2), 114; https://doi.org/10.3390/fermentation10020114 - 19 Feb 2024

Cited by 14 | Viewed by 4581

Abstract

This study investigated the combined impact of essential oil blends (EOBs) and fumaric acid (FA) on ruminal fermentation in dairy cows using the rumen simulation technique (RUSITEC) system. Three rumen-cannulated, non-lactating Holstein Friesian cows served as inoculum donors. The substrate, a total mixed [...] Read more.

This study investigated the combined impact of essential oil blends (EOBs) and fumaric acid (FA) on ruminal fermentation in dairy cows using the rumen simulation technique (RUSITEC) system. Three rumen-cannulated, non-lactating Holstein Friesian cows served as inoculum donors. The substrate, a total mixed ration (TMR), comprised corn silage, alfalfa hay, and a concentrate mix in a 3:1:1 ratio. The four treatments evaluated were Control (TMR without additives), EFA1 (TMR + EOB1 + FA), EFA2 (TMR + EOB2 + FA), and EFA3 (TMR + EOB3 + FA). Sixteen fermentation chambers were randomly assigned to the treatments, each with four replicates, following a completely randomized design during a 9-day experimental period. EOBs and FA were added at 10 µL/g feed and 3% of TMR, respectively. After a 4-day adaptation, samples were collected for 5 days. Results revealed that EFA1 significantly reduced (p = 0.0351) CH₄ emissions by 60.2% without negatively impacting dry matter disappearance, fiber fraction digestibility, pH, or gas volume. All EFAs increased (p < 0.001) the propionate molar proportion and decreased (p < 0.001) the acetate-to-propionate ratio. EFA2 decreased (p < 0.05) the acetate proportion by 3.3% compared to the control. In conclusion, EFA1 is recommended as an effective nutritional intervention to mitigate CH₄ emissions and optimize ruminal fermentation in dairy cows. Full article

(This article belongs to the Special Issue In Vitro Digestibility and Ruminal Fermentation Profile, 2nd Edition)

17 pages, 2284 KB

Open AccessEditor’s ChoiceArticle

Dynamic Optimization of Lactic Acid Production from Grape Stalk Solid-State Fermentation with Rhizopus oryzae Applying a Variable Temperature Profile

by María Carla Groff, Sandra Edith Noriega, Rocío Mariel Gil, Nadia Pantano and Gustavo Scaglia

Fermentation 2024, 10(2), 101; https://doi.org/10.3390/fermentation10020101 - 8 Feb 2024

Cited by 10 | Viewed by 4128

Abstract

Lactic acid is widely used in the food industry. It can be produced via chemical synthesis or biotechnological pathways by using renewable resources as substrates. The main challenge of sustainable production lies in reaching productivities and yields that allow for their industrial production. [...] Read more.

Lactic acid is widely used in the food industry. It can be produced via chemical synthesis or biotechnological pathways by using renewable resources as substrates. The main challenge of sustainable production lies in reaching productivities and yields that allow for their industrial production. In this case, the application of process engineering becomes a crucial tool to improve the performance of bioprocesses. In this work, we performed the solid-state fermentation of grape stalk using Rhizopus oryzae NCIM 1299 to obtain lactic acid, employing three different temperatures (22, 35, and 40 °C) and a relative humidity of 50%. The Logistic and First-Order Plus Dead Time models were adjusted for fungal biomass growth, and the Luedeking and Piret with Delay Time model was used for lactic acid production, obtaining higher R² values in all cases. At 40 °C, it was observed that Rhizopus oryzae grew in pellet form, resulting in an increase in lactic acid productivity. In this context, the effect of temperature on the kinetic parameters was evaluated with a polynomial correlation. Finally, using this correlation, a smooth and continuous optimal temperature profile was obtained by a dynamic optimization method, improving the final lactic acid concentration by 53%. Full article

(This article belongs to the Special Issue Fermented Foods: Traditional Processes, Innovative Strategies, and Challenges 2.0)

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18 pages, 8547 KB

Open AccessEditor’s ChoiceArticle

Mixotrophic Syngas Conversion Enables the Production of meso-2,3-butanediol with Clostridium autoethanogenum

by Anne Oppelt, Anton Rückel, Markus Rupp and Dirk Weuster-Botz

Fermentation 2024, 10(2), 102; https://doi.org/10.3390/fermentation10020102 - 8 Feb 2024

Cited by 9 | Viewed by 5471

Abstract

Providing simultaneously autotrophic and heterotrophic carbon sources is a promising strategy to overcome the limits of autotrophic syngas fermentations. D-xylose and L-arabinose are particularly interesting as they can be obtained by the hydrolysis of lignocellulosic biomass. The individual conversion of varying initial concentrations [...] Read more.

Providing simultaneously autotrophic and heterotrophic carbon sources is a promising strategy to overcome the limits of autotrophic syngas fermentations. D-xylose and L-arabinose are particularly interesting as they can be obtained by the hydrolysis of lignocellulosic biomass. The individual conversion of varying initial concentrations of these pentoses and D-fructose as reference was studied with C. autoethanogenum in fully controlled stirred-tank reactors with a continuous syngas supply. All mixotrophic batch processes showed increased biomass and product formation compared to an autotrophic reference process. Simultaneous CO and D-xylose or L-arabinose conversion was observed in contrast to D-fructose. In the mixotrophic batch processes with L-arabinose or D-xylose, the simultaneous CO and sugar conversion resulted in high final alcohol-to-acid ratios of up to 58 g g⁻¹. L-arabinose was superior as a mixotrophic carbon source because biomass and alcohol concentrations (ethanol and 2,3-butanediol) were highest, and significant amounts of meso-2,3-butanediol (>1 g L⁻¹) in addition to D-2,3-butanediol (>2 g L⁻¹) were solely produced with L-arabinose. Furthermore, C. autoethanogenum could not produce meso-2,3 butanediol under purely heterotrophic conditions. The mixotrophic production of meso-2,3-butanediol from L-arabinose and syngas, both available from residual lignocellulosic biomass, is very promising for use as a monomer for bio-based polyurethanes or as an antiseptic agent. Full article

(This article belongs to the Special Issue Microbial Fixation of CO₂ to Fuels and Chemicals)

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25 pages, 3178 KB

Open AccessEditor’s ChoiceArticle

Innovative Bicultured Lactic–Acetic Acid Co-fermentation Improves Jujube Puree’s Functionality and Volatile Compounds

by Turkson Antwi Boasiako, Yuqing Xiong, Isaac Duah Boateng, Jeffrey Appiagyei, Yanshu Li, Kerry Clark, Afusat Yinka Aregbe, Sanabil Yaqoob and Yongkun Ma

Fermentation 2024, 10(1), 71; https://doi.org/10.3390/fermentation10010071 - 21 Jan 2024

Cited by 15 | Viewed by 4793

Abstract

Jujubes (Ziziphus jujuba Mill), characterized by a rich profile of bioactive compounds, have been historically less exploited due to their unappealing sensory characteristics when dried, including delayed bitterness and a limited shelf life when fresh. Co-fermented jujube puree has emerged as a [...] Read more.

Jujubes (Ziziphus jujuba Mill), characterized by a rich profile of bioactive compounds, have been historically less exploited due to their unappealing sensory characteristics when dried, including delayed bitterness and a limited shelf life when fresh. Co-fermented jujube puree has emerged as a strategy for enhancing its functional food potential. This study examined the impact of 8-day bicultured Junzao jujube puree, employing both commercial and indigenous Chinese lactic and acetic acid bacteria. Our investigation encompassed an assessment of functionality (cellular profile, antioxidant properties, color, free amino acids, phenolic profiling, volatiles elucidation using headspace-solid phase microextraction gas chromatography–mass spectrometry (HS-SPME-GC-MS), aroma analysis using electronic nose), and microstructural analysis using scanning electron microscopy (SEM). Viable counts of bicultured purees showed probiotic effects exceeding 6–7 log CFU/mL. Strong positive correlations were observed between phenolic compounds (chlorogenic acid, rutin, p-coumaric acid) and antioxidant capacities (ABTS-RSA and DPPH-RSA). The darker color of raw jujube puree was modified, exemplified by a significant (p < 0.05) negative correlation between overall color difference and cyanidin 3-O-rutinoside (R² = −0.768). Purees, particularly those containing bicultures of Lactobacillus helveticus Lh 43 and Acetobacter pasteurianus Ap-As.1.41 HuNiang 1.01 exhibited the highest potential free amino acid content (157.17 ± 1.12 mg/100 g FW) compared to the control (184.03 ± 1.16 mg/100 g FW) with a distinctive formation of L-methionine in biculture of Lactiplantibacillus plantarum Lp 28 and A. pasteurianus Ap-As.1.41 HuNiang 1.01. The phenolic profile of Lacticaseibacillus casei Lc 122 and A. pasteurianus Ap-As.1.41 HuNiang 1.01 increased by 22.79% above the control (48.34 mg/100 g FW) while biculture: L. helveticus Lh 43 and A. pasteurianus Ap-As.1.41 HuNiang 1.01 were enhanced by 4.37%, with the lowest profile in Lp. plantarum Lp 28 and A. pasteurianus Ap-As.1.41 HuNiang 1.01 (46.85 mg/100 g FW). The electronic nose revealed the predominant presence of sulfur, terpenes, and alcohol sensor bioactives in the fermented purees. HS-SPME-GC-MS analysis identified 80 volatile compounds in the bicultured purees, with esters constituting the major group (42%). Furthermore, SEM analysis unveiled massive microscopic alterations in the bicultured purees compared to the unfermented puree. These results collectively demonstrated that lactic–acetic acid co-fermentation serves to biovalorize Junzao jujube puree, enhancing its organoleptic appeal and extending its shelf life. Full article

(This article belongs to the Special Issue Bioactivity Change in Fermented Foods)

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18 pages, 729 KB

Open AccessEditor’s ChoiceArticle

Non-Conventional Yeasts from Mozzarella Cheese Whey and Artisanal Sourdoughs: Leavening Capacity and Impact on Bread Sensory Profile

by Floriana Boscaino, Elena Ionata, Salvatore De Caro and Alida Sorrentino

Fermentation 2024, 10(1), 68; https://doi.org/10.3390/fermentation10010068 - 19 Jan 2024

Cited by 11 | Viewed by 4491

Abstract

Non-conventional yeasts (NCYs) (i.e., non-Saccharomyces) are used as alternative starters to promote aroma complexity of fermented foods (e.g., bakery products). A total of 66 yeasts isolated from artisanal food matrices (bread and pizza sourdoughs and milk whey) from different geographical areas [...] Read more.

Non-conventional yeasts (NCYs) (i.e., non-Saccharomyces) are used as alternative starters to promote aroma complexity of fermented foods (e.g., bakery products). A total of 66 yeasts isolated from artisanal food matrices (bread and pizza sourdoughs and milk whey) from different geographical areas of the Campania region (Italy) were screened for physiological and technological characteristics such as leavening ability, resistance to NaCl and pH, exopolysaccharide and phytase activity production, and carbohydrate assimilation. Selected and isolated microorganisms were also used to study the leavening kinetics in experimental doughs as mixed inocula of two different strains. Volatile organic compounds (VOCs) of the inoculated doughs were analyzed with solid-phase microextraction/gas chromatography–mass spectrometry (SPME/GC-MS). Most of the strains belonged to non-Saccharomyces species (Pichia kudriavzevii, Kluyveromyces marxianus) and Saccharomyces (S. cerevisiae). Several strains produced exopolysaccharides (EPSs), that are important for dough rheological properties. Moreover, yeasts isolated from whey showed extracellular phytase activity. The mixed starter culture of the S. cerevisiae and NCY strains showed a synergic effect that enhanced the doughs’ aroma complexity. The use of non-conventional yeasts mixed with S. cerevisiae strains can be advantageous in the bakery industry because they improve the bread aroma profiles and nutritional properties by bioactive molecule production. Full article

(This article belongs to the Special Issue New Aspect: Progress of Molds and Yeasts in Fermented-Food Production)

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20 pages, 3037 KB

Open AccessEditor’s ChoiceArticle

Biochemical Characterization of Three Heterologous Lactic Acid Bacteria Laccases from Pediococcus, Lactobacillus, and Lactococcus Genus and Their Potential to Degrade Biogenic Amines Using ABTS and Epicatechin as Mediators

by Isaac Monroy, Isidoro Olmeda, Sergi Ferrer and Isabel Pardo

Fermentation 2024, 10(1), 32; https://doi.org/10.3390/fermentation10010032 - 30 Dec 2023

Cited by 10 | Viewed by 4453

Abstract

In this study, we cloned and characterized three bacterial laccases from strains of the species Pediococcus parvulus, Lacticaseibacillus paracasei, and Lactococcus lactis isolated from wine and cheese and evaluated their biogenic amine degradation abilities in the presence/absence of artificial 2,2′-azinobis(3-ethylbenzothiazoline-6-sulphonic acid [...] Read more.

In this study, we cloned and characterized three bacterial laccases from strains of the species Pediococcus parvulus, Lacticaseibacillus paracasei, and Lactococcus lactis isolated from wine and cheese and evaluated their biogenic amine degradation abilities in the presence/absence of artificial 2,2′-azinobis(3-ethylbenzothiazoline-6-sulphonic acid (ABTS) or natural (epicatechin) mediator compounds. Although some recombinant bacterial laccases have been characterized and found to be biological tools for degrading biogenic amines with or without the use of mediators, no prior research has investigated the role of natural mediators, like phenolic substrates found in wine and certain vegetable foods, in the degradation of biogenic amines. The three recombinant bacterial laccases exhibited sigmoidal kinetics and had similar molecular mass but varied in k_0.5, k_cat, and specific activity toward ABTS. They are acidophilic and have an optimal temperature of 28 °C. However, they exhibit low thermal stability at temperatures higher than 37 °C. The three laccases were capable of degrading dopamine without the use of mediators, while the other amines were not degraded. The presence of ABTS enhanced the degradation of dopamine and tyramine, but the addition of epicatechin did not improve their degradation. This study presents a comparison of the laccases’ biogenic amine-degrading efficiency using different mediators. This is the first time such a comparison has been made. Full article

(This article belongs to the Section Microbial Metabolism, Physiology & Genetics)

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26 pages, 5115 KB

Open AccessEditor’s ChoiceArticle

Dip Hopping Technique and Yeast Biotransformations in Craft Beer Productions

by Paolo Passaghe, Lara Tat, Alba Goi, Luca Vit and Stefano Buiatti

Fermentation 2024, 10(1), 30; https://doi.org/10.3390/fermentation10010030 - 29 Dec 2023

Cited by 6 | Viewed by 4794

Abstract

This paper evaluates the effects of an alternative hopping technique, called dip hopping, on beer. This technique involves infusing hops in hot water (or in a portion of wort) and subsequently combining the infusion with the wort (after wort cooling) directly in the [...] Read more.

This paper evaluates the effects of an alternative hopping technique, called dip hopping, on beer. This technique involves infusing hops in hot water (or in a portion of wort) and subsequently combining the infusion with the wort (after wort cooling) directly in the fermenter when the yeast is added for fermentation. The reference beers were produced employing the “traditional” late hopping technique, and the experimental beers were produced using the dip hopping technique. A variety of hops with a significant concentration of essential oil and a strain of yeast with high β-glucosidic activity capable of releasing aromatic molecules from precursors supplied by hops were used. The samples were analysed in terms of alcohol content, degree of attenuation, colour, and bitterness. Sensory analysis and gas chromatography analysis were also performed. The data showed statistically significant differences between the reference beers and the experimental beers, with the latter featuring greater hints of citrus, fruity, floral, and spicy aromas. As an overall effect, there was an increase in the olfactory and gustatory pleasantness of the beers produced with the dip hopping technique. Full article

(This article belongs to the Special Issue Wine and Beer Fermentation)

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15 pages, 946 KB

Open AccessEditor’s ChoiceArticle

Biodiversity and Safety: Cohabitation Experimentation in Undefined Starter Cultures for Traditional Dairy Products

by Luigi Chessa, Elisabetta Daga, Ilaria Dupré, Antonio Paba, Maria C. Fozzi, Davide G. Dedola and Roberta Comunian

Fermentation 2024, 10(1), 29; https://doi.org/10.3390/fermentation10010029 - 29 Dec 2023

Cited by 9 | Viewed by 3085

Abstract

Natural starter cultures, characterised by undefined microbiota, can contribute to the technological process, giving peculiar characteristics to artisanal fermented foods. Several species have a long history of safe use and have obtained Qualified Presumption of Safety (QPS) status from the European Food Safety [...] Read more.

Natural starter cultures, characterised by undefined microbiota, can contribute to the technological process, giving peculiar characteristics to artisanal fermented foods. Several species have a long history of safe use and have obtained Qualified Presumption of Safety (QPS) status from the European Food Safety Authority (EFSA), whereas others (non-QPS) could represent a potential risk for consumers’ health and must undergo a safety assessment. In this work, the biodiversity, at species and strain level, by pulsed-field gel electrophoresis (PFGE) and (GTG)₅ rep-PCR, of an undefined natural starter culture, in frozen and lyophilized form, obtained from ewe’s raw milk avoiding thermal treatment or microbial selection, was investigated. The culture was constituted by different biotypes of Enterococcus durans, Enterococcus faecium, Enterococcus faecalis, and Lacticaseibacillus paracasei. Streptococcus oralis and Streptococcus salivarius were also found, over species belonging to the Streptococcus bovis–Streptococcus equinus complex (SBSEC), like Streptococcus gallolyticus subsp. macedonicus, Streptococcus lutetiensis, and Streptococcus equinus. Molecular investigation on virulence and antibiotic resistance genes, as well as minimum inhibitory concentration (MIC) determination, revealed that all the non-QPS strains can be considered safe in the perspective of using this culture for cheesemaking. The obtainment of a natural culture directly from ewe’s raw milk bypassing thermal treatment and selection of pro-technological bacteria can be advantageous in terms of biodiversity preservation, but non-QPS microorganisms can be included in the natural starter and also in cheeses, especially in traditional ones obtained from fermenting raw milk. Following EFSA guidelines, artisanal factories should not be allowed to produce starter cultures by themselves from raw milk, running the risk of including some non-QPS species in their culture, and only selected starters could be used for cheesemaking. A revision of the criteria of QPS guidelines should be necessary. Full article

(This article belongs to the Special Issue Development and Application of Starter Cultures)

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23 pages, 4827 KB

Open AccessEditor’s ChoiceArticle

Model Identification of E. coli Cultivation Process Applying Hybrid Crow Search Algorithm

by Olympia Roeva and Dafina Zoteva

Fermentation 2024, 10(1), 12; https://doi.org/10.3390/fermentation10010012 - 22 Dec 2023

Cited by 2 | Viewed by 2692

Abstract

Cultivation process (CP) modeling and optimization are ambitious tasks due to the nonlinear nature of the models and interdependent parameters. The identification procedures for such models are challenging. Metaheuristic algorithms exhibit promising performance for such complex problems since a near-optimal solution can be [...] Read more.

Cultivation process (CP) modeling and optimization are ambitious tasks due to the nonlinear nature of the models and interdependent parameters. The identification procedures for such models are challenging. Metaheuristic algorithms exhibit promising performance for such complex problems since a near-optimal solution can be found in an acceptable time. The present research explores a new hybrid metaheuristic algorithm built upon the good exploration of the genetic algorithm (GA) and the exploitation of the crow search algorithm (CSA). The efficiency of the proposed GA-CSA hybrid is studied with the model parameter identification procedure of the E. coli BL21(DE3)pPhyt109 fed-batch cultivation process. The results are compared with those of the pure GA and pure CSA applied to the same problem. A comparison with two deterministic algorithms, i.e., sequential quadratic programming (SQP) and the Quasi-Newton (Q-N) method, is also provided. A more accurate model is obtained by the GA-CSA hybrid with fewer computational resources. Although SQP and Q-N find a solution for a smaller number of function evaluations, the resulting models are not as accurate as the models generated by the three metaheuristic algorithms. The InterCriteria analysis, a mathematical approach to revealing certain relations between given criteria, and a series of statistical tests are employed to prove that there is a statistically significant difference between the results of the three stochastic algorithms. The obtained mathematical models are then successfully verified with a different set of experimental data, in which, again, the closest one is the GA-CSA model. The GA-CSA hybrid proposed in this paper is proven to be successful in the collaborative hybridization of GA and CSA with outstanding performance. Full article

(This article belongs to the Special Issue Modeling Methods for Fermentation Processes)

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13 pages, 5608 KB

Open AccessEditor’s ChoiceArticle

New Insights into the Biosynthesis of Succinic Acid by Actinobacillus succinogenes with the Help of Its Engineered Strains

by Chunmei Chen and Pu Zheng

Fermentation 2023, 9(12), 1026; https://doi.org/10.3390/fermentation9121026 - 15 Dec 2023

Cited by 13 | Viewed by 5165

Abstract

Succinic acid (SA), a C4 tricarboxylic acid cycle intermediate, is used as raw material for bulk chemicals and specialty chemicals, such as tetrahydrofuran and 1,4-butanediol, as well as also being used to synthesize the biodegradable biopolymers PBS (polymer poly (butylene succinate)). Actinobacillus succinogenes [...] Read more.

Succinic acid (SA), a C4 tricarboxylic acid cycle intermediate, is used as raw material for bulk chemicals and specialty chemicals, such as tetrahydrofuran and 1,4-butanediol, as well as also being used to synthesize the biodegradable biopolymers PBS (polymer poly (butylene succinate)). Actinobacillus succinogenes, which is facultative anaerobic and gram-negative, is one of the most promising natural SA-producing organisms, but genetic engineering of A. succinogenes is rare so far. In this study, a series of engineered strains was constructed using the pLGZ922 expression vector and a cytosine base editor (CBE) based on CRIPSR/Cas9; we found that phosphoenolpyruvate carboxylase (PEPC) was more important for the CO₂ fixation pathway than pyruvate carboxylase (PYC) in A. succinogenes, and the annotated oxaloacetic acid decarboxylase (Asuc_0301 and Asuc_0302) had little correlation with the SA synthesis pathway. The by-product pathway was closely related to cell growth, and overexpression of FDH was beneficial to growth, while the knockout of the ackA gene reduced the growth. For the first time, the hypothetic sugars and SA transporters were mined and identified in A. succinogenes, of which Asuc_0914 was responsible for glucose uptake, and Asuc_0715 and Asuc_0716 constituted SA exporters. This deepens the understanding of SA biosynthesis in A. succinogenes and is also valuable for SA production by fermentation. Full article

(This article belongs to the Section Microbial Metabolism, Physiology & Genetics)

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18 pages, 2818 KB

Open AccessEditor’s ChoiceArticle

The Application of Adaptive Model Predictive Control for Fed-Batch Escherichia coli BL21 (DE3) Cultivation and Biosynthesis of Recombinant Proteins

by Konstantins Dubencovs, Arturs Suleiko, Elina Sile, Ivars Petrovskis, Inara Akopjana, Anastasija Suleiko, Vytautas Galvanauskas, Kaspars Tars and Juris Vanags

Fermentation 2023, 9(12), 1015; https://doi.org/10.3390/fermentation9121015 - 12 Dec 2023

Cited by 6 | Viewed by 4868

Abstract

A model predictive control (MPC) method was investigated as a route to optimize and control the growth of E. coli BL21 (DE3) and biosynthesis of two different recombinant proteins (nerve growth factor NGF and coat protein of bacteriophage Qβ (Qβ-CP)). To determine the [...] Read more.

A model predictive control (MPC) method was investigated as a route to optimize and control the growth of E. coli BL21 (DE3) and biosynthesis of two different recombinant proteins (nerve growth factor NGF and coat protein of bacteriophage Qβ (Qβ-CP)). To determine the target trajectory for the E. coli cultivation process and estimate the model parameters, the off-line run-to-run optimization method was used. The proven method allowed us to successfully control the growth of microbial biomass, with a deviation of 6–12% from the target trajectory. It was proven that it is possible to obtain a “Golden Batch” profile for the implementation of MPC using datasets from only four to eight fermentation runs. The method showed its robustness when the cultivation of E. coli was carried out with two different titrant supply control systems—volumetric and gravimetric. Furthermore, the MPC method exhibited high adaptability, reliability, and resistance to various types of disturbances. MPC proved to be a reliable and effective method for controlling the cultivation and recombinant protein biosynthesis of fast-growing microorganisms such as E. coli. Full article

(This article belongs to the Section Microbial Metabolism, Physiology & Genetics)

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13 pages, 2310 KB

Open AccessEditor’s ChoiceArticle

Generation of a Culex Male Mosquito Sex-Separation RNAi Yeast Strain Using Cas-CLOVER and Super PiggyBac Engineering in Saccharomyces cerevisiae

by Corey Brizzee, Keshava Mysore, Teresia M. Njoroge, Seth McConnell, Jack Crawford and Molly Duman-Scheel

Fermentation 2023, 9(12), 999; https://doi.org/10.3390/fermentation9120999 - 23 Nov 2023

Cited by 2 | Viewed by 3517

Abstract

Several emerging mosquito control technologies require mass releases of adult male mosquitoes. Previous studies resulted in the generation of a laboratory female-specific larvicidal yeast strain targeting the GGT gene, which facilitated the laboratory sex separation of male Culex quinquefasciatus mosquitoes. Global deployment of [...] Read more.

Several emerging mosquito control technologies require mass releases of adult male mosquitoes. Previous studies resulted in the generation of a laboratory female-specific larvicidal yeast strain targeting the GGT gene, which facilitated the laboratory sex separation of male Culex quinquefasciatus mosquitoes. Global deployment of this yeast-based sex-separation technology requires engineering second generation yeast strains which can be used in industrial-scale fermentations to support global mosquito control programs. In this study, the RNA-guided Cas-CLOVER system was used in combination with piggyBac transposase to generate robust Saccharomyces cerevisiae strains with multiple integrated copies of the insecticidal GGT shRNA expression cassette. Top expressing Cas-CLOVER strains killed Culex quinquefasciatus female larvae which consumed the yeast, facilitating male sex separation. Scaled fermentation resulted in kilogram-scale production of the yeast, which can be heat-killed and dried for global deployment to mosquito mass-rearing facilities. Full article

(This article belongs to the Special Issue Advances in Yeast Biotechnology from Genomics to Industry)

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19 pages, 3232 KB

Open AccessEditor’s ChoiceArticle

Purified Acidic Sophorolipid Biosurfactants in Skincare Applications: An Assessment of Cytotoxic Effects in Comparison with Synthetic Surfactants Using a 3D In Vitro Human Skin Model

by Simms A. Adu, Matthew S. Twigg, Patrick J. Naughton, Roger Marchant and Ibrahim M. Banat

Fermentation 2023, 9(11), 985; https://doi.org/10.3390/fermentation9110985 - 18 Nov 2023

Cited by 7 | Viewed by 5591

Abstract

Acidic sophorolipids (Acidic SL), congeners of sophorolipid biosurfactants, offer a potential alternative to synthetic sodium lauryl ether sulphate (SLES) in skincare applications. However, major challenges associated with the laboratory-based investigations of the cytotoxic effects of Acidic SL have been the utilisation of impure [...] Read more.

Acidic sophorolipids (Acidic SL), congeners of sophorolipid biosurfactants, offer a potential alternative to synthetic sodium lauryl ether sulphate (SLES) in skincare applications. However, major challenges associated with the laboratory-based investigations of the cytotoxic effects of Acidic SL have been the utilisation of impure and/or poorly characterised congeners as well as the use of monolayers of skin cells in in vitro assays. While the former limitation makes glycolipids less attractive for use in academic research and skincare applications, the latter does not provide an accurate representation of the in vivo human skin. The present study, therefore, for the first time, assessed the cytotoxic effects of 96% pure Acidic SL on a 3D in vitro skin model in comparison with SLES, with the aim of investigating a natural alternative to synthetic surfactants for potential use in skincare applications. The 3D in vitro skin model was colonised with Staphylococcus epidermidis for 12 h, and afterwards treated with either Acidic SL or SLES at 100 μg mL⁻¹ for a further 12 h. Subsequently, the cytotoxic effects of Acidic SL in comparison with SLES were assessed using a combination of microbiology, molecular biology techniques, immunoassays, and histological analyses. It was demonstrated that Acidic SL had no deleterious effects on the viability of S. epidermidis, tissue morphology, filaggrin expression, and the production of inflammatory cytokines in comparison to SLES. These findings, in conjunction with the possibility to produce Acidic SL from cheaper renewable natural resources, demonstrate that Acidic SL could offer a potential sustainable alternative to synthetic surfactants. Full article

(This article belongs to the Special Issue Production and Application of Bioactive Biosurfactants)

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17 pages, 10207 KB

Open AccessEditor’s ChoiceArticle

Monitoring β-Fructofuranosidase Activity through Kluyveromyces marxianus in Bioreactor Using a Lab-Made Sequential Analysis System

by Edwin J. Barbosa-Hernández, Jorge E. Pliego-Sandoval, Anne Gschaedler-Mathis, Javier Arrizon-Gaviño, Alejandro Arana-Sánchez, Ricardo Femat and Enrique J. Herrera-López

Fermentation 2023, 9(11), 963; https://doi.org/10.3390/fermentation9110963 - 10 Nov 2023

Cited by 4 | Viewed by 3531

Abstract

The yeast Kluyveromyces marxianus has shown the potential to produce

β

-fructofuranosidases, which are enzymes capable of hydrolyzing

β

-fructofuranosides links of fructans to obtain fructooligosaccharides. The thriving market for fructose syrup and the quality standards imposed by food and pharmaceutical industries have [...] Read more.

The yeast Kluyveromyces marxianus has shown the potential to produce

β

-fructofuranosidases, which are enzymes capable of hydrolyzing

β

-fructofuranosides links of fructans to obtain fructooligosaccharides. The thriving market for fructose syrup and the quality standards imposed by food and pharmaceutical industries have generated an increased search for improved, monitored, and controlled production processes. Monitoring

β

-fructofuranosidase activity in a bioprocess requires the use of adequate sensors and the processing of information using efficient software algorithms; nevertheless, currently, such a sensor does not exist for this purpose. In this contribution, a sequential injection analysis system (SIA) developed in our laboratory was adapted to monitor at-line

β

-fructofuranosidase activity produced by the yeast K. marxianus. Samples were taken out automatically from the bioreactor and analyzed using 3,5-dinitrosalicylic (DNS). An algorithm was designed to operate the overall components of the lab-made SIA system. The enzymatic activity error obtained with the automatic SIA compared to the off-line laboratory determinations varied from 0.07% at high enzyme concentrations to 20.39% at low

β

-fructofuranosidase activity. Further development is required to improve the performance of the lab-made SIA system; nevertheless, such a device must be considered as a potential method for monitoring

β

-fructofuranosidase activity in real time. Full article

(This article belongs to the Special Issue Fermentation Processes: Modeling, Optimization and Control)

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15 pages, 931 KB

Open AccessEditor’s ChoiceArticle

Oxidative Phosphorylation for Aerobic Survival, but Not for Growth: The Peculiar ‘Make-Accumulate-Consume’ Strategy in Zymomonas mobilis

by Inese Strazdina, Mara Bikerniece, Evelina Rezija Paegle, Karlis Shvirksts, Mara Grube, Zane Lasa, Reinis Rutkis and Uldis Kalnenieks

Fermentation 2023, 9(11), 951; https://doi.org/10.3390/fermentation9110951 - 2 Nov 2023

Cited by 3 | Viewed by 3299

Abstract

Understanding the energy metabolism and its regulation is one of the clues to metabolic engineering of stress-resistant lignocellulose-converting microbial strains, also including the promising ethanologen Zymomonas mobilis. Z. mobilis is an obligately fermentative, facultatively anaerobic bacterium, carrying an active respiratory chain with [...] Read more.

Understanding the energy metabolism and its regulation is one of the clues to metabolic engineering of stress-resistant lignocellulose-converting microbial strains, also including the promising ethanologen Zymomonas mobilis. Z. mobilis is an obligately fermentative, facultatively anaerobic bacterium, carrying an active respiratory chain with low energy-coupling efficiency. Its respiration does not supply energy to aerobically growing cultures on sugary media, yet oxidative phosphorylation has been demonstrated in non-growing cells with ethanol. Here, we show, for the first time, that in respiring, non-growing Z. mobilis cells receiving regular small amounts of ethanol, oxidative phosphorylation significantly contributes to the maintenance of their viability. No improvement of viability is seen in the NADH dehydrogenase (ndh)-deficient respiratory mutant, which is unable to oxidize ethanol. The ethanol effect is also hampered by the protonophoric uncoupler CCCP, or the inhibitor of ATP synthase, DCCD. At higher concentrations (6% v/v), ethanol causes stress that slows down culture growth. By monitoring the activity of several respiratory gene promoters under ethanol stress with the green fluorescent protein reporter system, we demonstrate downregulation of these promoters, in particular the ndh promoter. We speculate that the decrease in respiratory chain activity in response to stress conditions mitigates the production of reactive oxygen species. Full article

(This article belongs to the Special Issue Bioconversion of Lignocellulosic Materials to Value-Added Products 2.0)

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17 pages, 6154 KB

Open AccessEditor’s ChoiceArticle

Innocell Bioreactor: An Open-Source Development to Produce Biomaterials for Food and Packaging Based on Fermentation Processes

by Nitzan Cohen, Emma Sicher, Camilo Ayala-Garcia, Ignacio Merino Sanchez-Fayos, Lorenza Conterno and Secil Ugur Yavuz

Fermentation 2023, 9(10), 915; https://doi.org/10.3390/fermentation9100915 - 18 Oct 2023

Cited by 5 | Viewed by 8452

Abstract

A growing number of science and design scholars and design practitioners have recently embarked on studying fermentation processes to produce alternative materials. The main driver of this trend is the search for a sustainable future by proposing novel alternatives that could substitute or [...] Read more.

A growing number of science and design scholars and design practitioners have recently embarked on studying fermentation processes to produce alternative materials. The main driver of this trend is the search for a sustainable future by proposing novel alternatives that could substitute or integrate into society’s current production and consumption models. This study presents the development of an open-source bioreactor capable of enhancing and optimizing a symbiotic culture of bacteria and yeast (SCOBY) production process. The bioreactor is part of a greater design-driven project aiming to process edible and non-edible materials. The study presents the experiments and methods that led to the development and refinement of the current bioreactor, and all the information needed to replicate it with tools and equipment currently available under the Creative Commons status. The aim of sharing open-source methods and results to reproduce the bioreactor is to support different interdisciplinary teams of scientists and designers in generating high amounts of SCOBY, accelerating R&D with this auspicious yet underexplored source of bacterial cellulose. Full article

(This article belongs to the Special Issue Modeling Methods for Fermentation Processes)

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12 pages, 11523 KB

Open AccessEditor’s ChoiceArticle

Engineering the C3N Pathway as a Short Detour for De Novo NAD⁺ Biosynthesis in Saccharomyces cerevisiae

by Xinli Li, Yue Tang, Yong Ding, Pengwei Li and Yihua Chen

Fermentation 2023, 9(10), 886; https://doi.org/10.3390/fermentation9100886 - 29 Sep 2023

Cited by 1 | Viewed by 2871

Abstract

As a life-essential coenzyme, nicotinamide adenine dinucleotide (NAD⁺) has been explored for more than a century. In Saccharomyces, the natural NAD⁺de novo biosynthetic pathway initiating from tryptophan has been well elucidated. To bypass this stringently controlled natural pathway [...] Read more.

As a life-essential coenzyme, nicotinamide adenine dinucleotide (NAD⁺) has been explored for more than a century. In Saccharomyces, the natural NAD⁺de novo biosynthetic pathway initiating from tryptophan has been well elucidated. To bypass this stringently controlled natural pathway in yeast, an economical C3N pathway that was developed in Escherichia coli previously was constructed in Saccharomyces as a short detour for de novo NAD⁺ biosynthesis. After the functional expressions of the C3N genes were identified in Saccharomyces cerevisiae BY4741 by in vitro enzymatic assays, the C3N module was introduced into an NAD⁺ auxotrophic S. cerevisiae strain BY01, in which the BNA2 gene encoding tryptophan 2,3-dioxygenase was inactivated. The efficient NAD⁺ synthesis via the C3N pathway was confirmed by both plate assays and fermentation analysis. The applicability of the C3N pathway in cofactor engineering was tested by introducing it into S. cerevisiae BY4741, which improved the cellular NAD(H) level considerably. Consequently, this study proved that the de novo NAD⁺ biosynthetic pathway can be replaced by an artificial pathway in yeast, which paves a way to design more promising schemes in eukaryotes for rational manipulation of the cellular NAD(H) levels. Full article

(This article belongs to the Special Issue Research on Microbial Transformation and Biosynthesis of Enzymes)

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18 pages, 1478 KB

Open AccessEditor’s ChoiceArticle

Exploitation of Cocoa Pod Residues for the Production of Antioxidants, Polyhydroxyalkanoates, and Ethanol

by Licelander Hennessey Ramos, Miluska Cisneros-Yupanqui, Diana Vanessa Santisteban Soto, Anna Lante, Lorenzo Favaro, Sergio Casella and Marina Basaglia

Fermentation 2023, 9(9), 843; https://doi.org/10.3390/fermentation9090843 - 14 Sep 2023

Cited by 25 | Viewed by 6540

Abstract

Cocoa pod husks (CPH) and cocoa bean shells (CBS) are the main by-products of the cocoa industry and a source of bioactive compounds. These residues are not completely used and thrown in the fields without any treatment, causing environmental problems. Looking for a [...] Read more.

Cocoa pod husks (CPH) and cocoa bean shells (CBS) are the main by-products of the cocoa industry and a source of bioactive compounds. These residues are not completely used and thrown in the fields without any treatment, causing environmental problems. Looking for a holistic valorization, the aim of this work was first to deeply characterize CPH and CBS in their chemical composition, amino acid, and fatty acid profiles, as well as their application as antioxidants. CBS had a high level of protein (17.98% DM) and lipids (16.24% DM) compared with CPH (4.79 and 0.35% DM respectively). Glutamic acid and aspartic acid were the predominant amino acids. The total phenolic compounds (TPC) detected in the ethanolic extracts of CPH and CBS were similar to pyrogallol as the main detected polyphenol (72.57 mg/L). CBS ethanolic extract showed a higher antioxidant activity than CPH. Both extracts increased the oxidation stability of soybean oil by 48% (CPH) and 32% (CBS). In addition, alkaline pretreatment of CPH was found suitable for the release of 15.52 ± 0.78 g glucose/L after subsequent saccharification with the commercial enzyme Cellic^®. CTec2. Alkaline hydrolyzed and saccharified CPH (Ahs-CPH) was assessed for the first time to obtain polyhydroxy alkanoate (PHAs) and bioethanol. Ahs-CPH allowed the growth of both Cupriavidus necator DSM 545 and Saccharomyces cerevisiae Fm17, well-known as PHA- and bioethanol-producing microbes, respectively. The obtained results suggest that such agricultural wastes have interesting characteristics with new potential industrial uses that could be a better alternative for the utilization of biomass generated as million tons of waste annually. Full article

(This article belongs to the Special Issue Sustainable Development of Food Waste Biorefineries)

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17 pages, 3408 KB

Open AccessEditor’s ChoiceArticle

Acetate Production by Moorella thermoacetica via Syngas Fermentation: Effect of Yeast Extract and Syngas Composition

by Budi Mandra Harahap and Birgitte K. Ahring

Fermentation 2023, 9(9), 826; https://doi.org/10.3390/fermentation9090826 - 9 Sep 2023

Cited by 18 | Viewed by 4698

Abstract

Gasifiers produce a gaseous mixture of CO/CO₂/H₂, also known as synthesis gas (syngas), containing varying compositions and ratios depending on the lignocellulose material types, gasifier design, and gasification conditions. Different physicochemical and thermodynamic properties of each gas type in [...] Read more.

Gasifiers produce a gaseous mixture of CO/CO₂/H₂, also known as synthesis gas (syngas), containing varying compositions and ratios depending on the lignocellulose material types, gasifier design, and gasification conditions. Different physicochemical and thermodynamic properties of each gas type in the various syngas blends can influence syngas fermentation performance for the production of chemicals such as acetate. This study examined the effect of syngas composition (CO, CO/H₂, CO/CO₂/H₂, and CO/H₂) and its corresponding ratio on acetate production using Moorella thermoacetica, a thermophilic homoacetogen as the biocatalyst. We also investigated the effect of yeast extract addition for enhancing acetate production. A syngas fermentation study performed at a total pressure of 19 psig (2.29 atm) demonstrated that syngas fermentation in the absence of CO (30%CO₂/70%H₂) or at low CO proportions (21%CO/24%CO₂/55%H₂) resulted in the highest volumetric productivity of acetate (0.046 ± 0.001 and 0.037 ± 0.001 g/L/h, respectively). Interestingly, syngas fermentation without CO reached the highest Y_P/X of 22.461 ± 0.574 g-acetate/g-biomass, indicating that more acetate was produced compared to cell biomass. Higher biomass production was obtained when the CO proportion was increased up to 75% in CO/H₂ fermentation. However, the cell growth and acetate production dramatically decreased with increasing CO proportion up to 99.5% CO as the sole constituent of the syngas. Even so, acetate production using 99.5% CO could be improved by adding 2 g/L yeast extract. Full article

(This article belongs to the Special Issue Recent Advances in Syngas Fermentation)

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16 pages, 1056 KB

Open AccessEditor’s ChoiceArticle

Lactic Acid Production from Steam-Exploded Sugarcane Bagasse Using Bacillus coagulans DSM2314

by William Rodrigues Alves, Thiago Alessandre da Silva, Arion Zandoná Filho and Luiz Pereira Ramos

Fermentation 2023, 9(9), 789; https://doi.org/10.3390/fermentation9090789 - 26 Aug 2023

Cited by 15 | Viewed by 4956

Abstract

This work aimed at producing lactic acid (LA) from sugarcane bagasse after steam explosion at 195 °C for 7.5 and 15 min. Enzymatic hydrolysis was carried out with Cellic CTec3 and Cellic HTec3 (Novozymes), whereas fermentation was performed with Bacillus coagulans DSM2314. Water [...] Read more.

This work aimed at producing lactic acid (LA) from sugarcane bagasse after steam explosion at 195 °C for 7.5 and 15 min. Enzymatic hydrolysis was carried out with Cellic CTec3 and Cellic HTec3 (Novozymes), whereas fermentation was performed with Bacillus coagulans DSM2314. Water washing of pretreated solids before enzymatic hydrolysis improved both hydrolysis and fermentation yields. The presence of xylo-oligosaccharides (XOS) in substrate hydrolysates reduced hydrolysis efficiency, but their effect on fermentation was negligible. The presence of fermentation inhibitors in C5 streams was circumvented by adsorption on activated carbon powder with no detectable sugar losses. High carbohydrates-to-LA conversions (Y_p/s) of 0.88 g·g⁻¹ were obtained from enzymatic hydrolysates of water-washed steam-exploded materials that were produced at 195 °C, in 7.5 min, and the use of centrifuged-but-never-washed pretreated solids decreased Y_p/s by 16%. However, when the detoxified C5 stream was added at a 10% ratio, Y_p/s was raised to 0.93 g·g⁻¹ for an LA productivity of 2.55 g·L⁻¹·h⁻¹. Doubling the pretreatment time caused a decrease in Y_p/s to 0.78 g·g⁻¹, but LA productivity was the highest (3.20 g·L⁻¹·h⁻¹). For pretreatment at 195 °C for 7.5 min, the elimination of water washing seemed feasible, but the use of longer pretreatment times made it mandatory to eliminate fermentation inhibitors. Full article

(This article belongs to the Special Issue Upstream Bioprocesses to Biomass-Based Platform Chemicals and Derivatives)

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12 pages, 1247 KB

Open AccessEditor’s ChoiceArticle

Evaluation of Long-Term Fermentation Performance with Engineered Saccharomyces cerevisiae Strains

by Maarten L. De Mol, Victoria Marcoen, Isabelle Maryns, Nico Snoeck, Joeri J. Beauprez, Sofie L. De Maeseneire and Wim K. Soetaert

Fermentation 2023, 9(8), 721; https://doi.org/10.3390/fermentation9080721 - 30 Jul 2023

Cited by 7 | Viewed by 5587

Abstract

The performance of a microbial fermentation on an industrial scale is subjected to the robustness of the strain. Such strains are genetically engineered to optimize the production of desired compounds in minimal time, but they often fail to maintain high productivity levels for [...] Read more.

The performance of a microbial fermentation on an industrial scale is subjected to the robustness of the strain. Such strains are genetically engineered to optimize the production of desired compounds in minimal time, but they often fail to maintain high productivity levels for many generations, hindering their effective application in industrial conditions. This study focused on assessing the impact of genomic instability in yeasts that were engineered to produce a fluorescent output by incorporating a reporter gene at one or more genomic locations. The fermentation performance of these strains was evaluated over 100 generations in a sequential batch set-up. In order to bridge the gap between strain engineering and industrial implementation, we proposed the use of novel, host-specific parameters to standardize the strain robustness and evaluate potential improvements. It was observed that yeasts carrying multiple copies of the reporter gene exhibited a more pronounced decrease in output, and the genomic integration site significantly influenced the production. By leveraging these new, host-specific parameters, it becomes possible to anticipate strain behavior prior to incurring substantial costs associated with large-scale production. This approach enhances the economic viability of novel microbial fermentation processes and narrows the divide between laboratory findings and industrial applications. Full article

(This article belongs to the Special Issue Modeling Methods for Fermentation Processes)

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12 pages, 1491 KB

Open AccessEditor’s ChoiceArticle

Feasibility Study of Biohydrogen Production from Acid Cheese Whey via Lactate-Driven Dark Fermentation

by Brenda Aranda-Jaramillo, Elizabeth León-Becerril, Oscar Aguilar-Juárez, Roberto Castro-Muñoz and Octavio García-Depraect

Fermentation 2023, 9(7), 644; https://doi.org/10.3390/fermentation9070644 - 9 Jul 2023

Cited by 37 | Viewed by 5767

Abstract

The high loading of lactic acid bacteria (LAB) present in cheese whey still limits its use as hydrogen feedstock. This study aims to investigate the feasibility of producing hydrogen from acid cheese whey via lactate-driven dark fermentation (LD-DF). Mesophilic batch fermentations were performed [...] Read more.

The high loading of lactic acid bacteria (LAB) present in cheese whey still limits its use as hydrogen feedstock. This study aims to investigate the feasibility of producing hydrogen from acid cheese whey via lactate-driven dark fermentation (LD-DF). Mesophilic batch fermentations were performed with delipidated acid cheese whey at a fixed pH of 5.8 and driven by an acidogenic bacterial culture containing LAB and lactate-oxidizing hydrogen producers (LO-HPB). The results obtained indicated that it is technically feasible to produce hydrogen from undiluted cheese whey through lactate oxidation-mediated fermentation. It was elucidated that the acidogenic fermentation of cheese whey followed a two-step lactate-type fermentation, in which fermentable carbohydrates were first converted into lactate, and then lactate was metabolized into hydrogen with the co-production of butyrate. The hydrogen yield and the maximum volumetric hydrogen production rate achieved were 44.5 ± 2.9 NmL/g-COD_fed and 1.9 NL/L-d, respectively. Further microbial community analysis revealed that Lactobacillus, Clostridium, and Klebsiella were the dominant bacterial genera when the hydrogen production rate peaked. It was therefore suggested that the metabolic potential behind the association between LAB and LO-HPB was important in driving the two-step lactate-type fermentation. Overall, the LD-DF can be a strategic hydrogen-producing pathway to be implemented with cheese whey. Full article

(This article belongs to the Special Issue Organic Waste Valorization into Bioenergy and Biochemicals with High Industrial Interest)

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16 pages, 2498 KB

Open AccessEditor’s ChoiceArticle

Effects of Temperature Shifts on Microbial Communities and Biogas Production: An In-Depth Comparison

by Gede Adi Wiguna Sudiartha, Tsuyoshi Imai, Chonticha Mamimin and Alissara Reungsang

Fermentation 2023, 9(7), 642; https://doi.org/10.3390/fermentation9070642 - 8 Jul 2023

Cited by 50 | Viewed by 6738

Abstract

Temperature plays a significant role in anaerobic digestion (AD) as it affects the microbial communities and ultimately controls the efficiency of the process. Few studies have looked at temperature-adjusted AD, but it is unclear how the temperature shifts affect biogas production and the [...] Read more.

Temperature plays a significant role in anaerobic digestion (AD) as it affects the microbial communities and ultimately controls the efficiency of the process. Few studies have looked at temperature-adjusted AD, but it is unclear how the temperature shifts affect biogas production and the dynamics of microorganisms involved in methanogenesis. This study tested two temperature shift scenarios in fed-batch mode using anaerobically digested sewage sludge and glucose-based substrate. The first scenario was acclimatized to upshifting temperatures from 42 °C to 48 °C while the second was acclimatized to downshifting temperatures from 55 °C to 45 °C. Both temperature shift scenarios resulted in a decrease in biogas production, especially at 45 °C. The upshifted scenario experienced a maximum decrease of 83%, and the downshifted scenario experienced a 16–33% decrease in methane production. Next-generation 16S rRNA sequencing revealed the domination of Methanoculleus in the upshifted scenario. However, a low correlation between the number of Methanoculleus and the other hydrogenotrophic methanogens to biogas production indicates inhibition in the hydrogenotrophic pathway. The downshifted scenario showed better biogas production due to the substantial domination of acetoclastic Methanosaeta and the low abundance of sulfate-reducing bacteria. Hence, the temperature shift affects the microbial communities, significantly affecting biogas production performance. Full article

(This article belongs to the Special Issue Anaerobic Digestion: Waste to Energy)

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19 pages, 2780 KB

Open AccessEditor’s ChoiceArticle

Automatic Control of Chemolithotrophic Cultivation of Cupriavidus necator: Optimization of Oxygen Supply for Enhanced Bioplastic Production

by Vera Lambauer, Alexander Permann, Zdeněk Petrášek, Vanja Subotić, Christoph Hochenauer, Regina Kratzer and Markus Reichhartinger

Fermentation 2023, 9(7), 619; https://doi.org/10.3390/fermentation9070619 - 29 Jun 2023

Cited by 21 | Viewed by 6757

Abstract

Gas fermentation is an upcoming technology to convert gaseous substrates into value-added products using autotrophic microorganisms. The hydrogen-oxidizing bacteria Cupriavidus necator efficiently uses CO₂ as its sole carbon source, H₂ as electron donor and O₂ as electron acceptor. Surplus CO [...] Read more.

Gas fermentation is an upcoming technology to convert gaseous substrates into value-added products using autotrophic microorganisms. The hydrogen-oxidizing bacteria Cupriavidus necator efficiently uses CO₂ as its sole carbon source, H₂ as electron donor and O₂ as electron acceptor. Surplus CO₂ is stored in microbial storage material poly-(R)-3-hydroxybutyrate. O₂ supply is the most critical parameter for growth and poly-(R)-3-hydroxybutyrate formation. A narrow O₂ optimum between ~0.2 and ~4 mg/L was previously reported. Here, a standard benchtop bioreactor was redesigned for autotrophic growth of C. necator on explosive mixtures of CO₂, H₂ and O₂. The bioreactor was equipped with mass flow control units and O₂ and CO₂ sensors. A controller for automated gas dosage based on a mathematical model including gas mass transfer, gas consumption and sensor response time was developed. Dissolved O₂ concentrations were adjusted with high precision to 1, 2 and 4% O₂ saturation (0.4, 0.8 and 1.5 mg/L dissolved O₂, respectively). In total, up to 15 g/L cell dry weight were produced. Residual biomass formation was 3.6 ± 0.2 g/L under all three O₂ concentrations. However, poly-(R)-3-hydroxybutyrate content was 71, 77 and 58% of the cell dry weight with 1, 2 and 4% dissolved O₂, respectively. Full article

(This article belongs to the Special Issue Biomass Conversion, CO₂ Valorisation and Power-to-X: Fermentation Chemicals and Fuels)

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