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Fermentation, Volume 8, Issue 7 (July 2022) – 53 articles

Cover Story (view full-size image): The need for alternative energy sources is constantly growing, while the focus has shifted to biomass valorization. The aim of this study was to determine the optimal pH and hydraulic retention time (HRT) for treating, through anaerobic digestion, a sorghum biomass and cow manure mixture. Both batch and CSTR systems are run for the investigation of the effect of pH on H2 and volatile fatty acids (VFAs) maximization as well as for the effect of HRT on H2 and CH4 production, respectively. The batch tests exhibited that pH values of 5 and 6 favored H2 and VFAs, respectively, while the two-stage CSTR system showed that the most efficient HRTs were 5 d (acidogenesis) and 25 d (methanogenesis). Reduced HRTs led to inhibition or overload, as indicated by the biogas productivity decline. View this paper
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13 pages, 2423 KiB  
Article
High-Level Production of Catechol from Glucose by Engineered Escherichia coli
by Guotian Song, Fengli Wu, Yanfeng Peng, Xiaolong Jiang and Qinhong Wang
Fermentation 2022, 8(7), 344; https://doi.org/10.3390/fermentation8070344 - 21 Jul 2022
Cited by 3 | Viewed by 2637
Abstract
Catechol (CA) is an aromatic compound with important applications in the fine chemical and pharmaceutical fields. As an alternative strategy to petroleum-based chemical synthesis, the production of catechol by using microbial cell factories has attracted great interest. However, the toxicity of catechol to [...] Read more.
Catechol (CA) is an aromatic compound with important applications in the fine chemical and pharmaceutical fields. As an alternative strategy to petroleum-based chemical synthesis, the production of catechol by using microbial cell factories has attracted great interest. However, the toxicity of catechol to microbial cells significantly limits the efficient production of bio-based catechol via one-step fermentation. Therefore, in this study, a two-step strategy for the efficient synthesis of CA was designed. Protocatechuic acid (PCA) was first efficiently produced by the engineered Escherichia coli strain AAA01 via fermentation, and then PCA in the fermentative broth was converted into CA by the whole-cell biocatalyst AAA12 with PCA decarboxylase. By optimizing the expression of flavin isoprenyl transferases and protocatechuic acid decarboxylases, the titer of CA increased from 3.4 g/L to 15.8 g/L in 12 h through whole-cell biocatalysis, with a 365% improvement; after further optimizing the reaction conditions for whole-cell biocatalysis, the titer of CA achieved 17.7 g/L within 3 h, which is the highest titer reported so far. This work provides an effective strategy for the green biomanufacturing of toxic compounds by Escherichia coli cell factories. Full article
(This article belongs to the Section Microbial Metabolism, Physiology & Genetics)
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15 pages, 4015 KiB  
Article
Colaconema formosanum, Sarcodia suae, and Nostoc commune as Fermentation Substrates for Bioactive Substance Production
by Meng-Chou Lee, Chin-Yi Huang, Chin-Ling Lai, Han-Yang Yeh, Jing Huang, Wei Qing Chloe Lung, Po-Tsang Lee and Fan-Hua Nan
Fermentation 2022, 8(7), 343; https://doi.org/10.3390/fermentation8070343 - 21 Jul 2022
Cited by 3 | Viewed by 1916
Abstract
Bioactive compounds extracted from natural renewable sources have attracted an increased interest from both industry and academia. Recently, algae have been highlighted as promising sources of bioactive compounds, such as polyphenols, polysaccharides, fatty acids, proteins, and pigments, which can be used as functional [...] Read more.
Bioactive compounds extracted from natural renewable sources have attracted an increased interest from both industry and academia. Recently, algae have been highlighted as promising sources of bioactive compounds, such as polyphenols, polysaccharides, fatty acids, proteins, and pigments, which can be used as functional ingredients in many industrial applications. Therefore, a simple green extraction and purification methodology capable of recovering biocompounds from algal biomass is of extreme importance in commercial production. In this study, we evaluated the application of three valuable algae (Colaconema formosanum, Sarcodia suae, and Nostoc commune) in combination with Pseudoalteromonas haloplanktis (type strain ATCC 14393) for the production of versatile compounds. The results illustrate that after 6 h of first-stage fermentation, the production of phycobiliproteins in C. formosanum was significantly increased by 156.2%, 188.9%, and 254.17% for PE, PC, and APC, respectively. This indicates that the production of phycobiliproteins from algae can be enhanced by P. haloplanktis. Furthermore, we discovered that after S. suae and N. commune were fermented with P. haloplanktis, mannose was produced. In this study, we describe a feasible biorefinery process for the production of phycobiliproteins and mannose by fermenting marine macroalgae with cyanobacteria. We believe it is worth establishing a scale-up technique by applying this fermentation method to the production of phycobiliproteins and mannose in the future. Full article
(This article belongs to the Special Issue Pigment Production in Submerged Fermentation)
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11 pages, 1211 KiB  
Article
Bacterial Diversity and Dynamics during Spontaneous Cheese Whey Fermentation at Different Temperatures
by Miguel A. Mazorra-Manzano, Glen R. Robles-Porchas, Marcel Martínez-Porchas, Juan C. Ramírez-Suárez, Celia O. García-Sifuentes, María J. Torres-Llanez, Aarón F. González-Córdova, Adrián Hernández-Mendoza and Belinda Vallejo-Cordoba
Fermentation 2022, 8(7), 342; https://doi.org/10.3390/fermentation8070342 - 20 Jul 2022
Cited by 5 | Viewed by 1947
Abstract
The effect of temperature (32–50 °C) on bacterial dynamics and taxonomic structure was evaluated during spontaneous whey fermentation for lactic acid production. Bacterial plate count in fresh whey (5 log CFU/mL) increased in two orders of magnitude after 60 h of fermentation (7 [...] Read more.
The effect of temperature (32–50 °C) on bacterial dynamics and taxonomic structure was evaluated during spontaneous whey fermentation for lactic acid production. Bacterial plate count in fresh whey (5 log CFU/mL) increased in two orders of magnitude after 60 h of fermentation (7 log CFU/mL), followed by one log reduction after 120 h (6 log CFU/mL) at 37 and 42 °C. Streptococcus and Lactobacillus counts ranged between 5–9 and 5–8 log CFU/mL, respectively. High-throughput sequencing of the 16S rRNA gene (V3-V4 region) used as a taxonomic marker revealed thirteen different bacterial phyla. Actinobacteria, Bacteroidetes, Firmicutes, and Proteobacteria were detected in all fermentation treatments (32–50 °C, 0–120 h), where Firmicutes was the predominant phylum. Bacterial diversity included more than 150 bacterial genera with predominant lactic acid bacteria (belonging to Firmicutes) such as Lactobacillus, Lactococcus, Streptococcus, and Tetragenococcus. At the species level, fresh whey presented 61 predominant species (relative abundance > 0.05%); however, only 57.4% of these resisted the fermentation conditions (most of them belonging to lactic acid bacteria genera). Tetragenococcus halophilus, Lactococcus lactis, and Enterococcus casseliflavus were the predominant bacteria found in all treatments. Temperatures between 37–42 °C were more favorable for lactic acid production and could be considered appropriate conditions for fermented whey production and for the standardization of some artisanal cheese-making processes requiring acid whey addition for milk coagulation. The diversity of native beneficial bacteria found in fresh whey offers attractive technological characteristics, and their fermentative capacity would represent a biotechnological option to add value to cheese whey. Full article
(This article belongs to the Special Issue Recent Trends in Lactobacillus and Fermented Food)
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16 pages, 2837 KiB  
Article
Recycling Food Waste and Saving Water: Optimization of the Fermentation Processes from Cheese Whey Permeate to Yeast Oil
by Silvia Donzella, Andrea Fumagalli, Stefania Arioli, Luisa Pellegrino, Paolo D’Incecco, Francesco Molinari, Giovanna Speranza, Daniela Ubiali, Marina S. Robescu and Concetta Compagno
Fermentation 2022, 8(7), 341; https://doi.org/10.3390/fermentation8070341 - 19 Jul 2022
Cited by 18 | Viewed by 3675
Abstract
With the aim of developing bioprocesses for waste valorization and a reduced water footprint, we optimized a two-step fermentation process that employs the oleaginous yeast Cutaneotrichosporon oleaginosus for the production of oil from liquid cheese whey permeate. For the first step, the addition [...] Read more.
With the aim of developing bioprocesses for waste valorization and a reduced water footprint, we optimized a two-step fermentation process that employs the oleaginous yeast Cutaneotrichosporon oleaginosus for the production of oil from liquid cheese whey permeate. For the first step, the addition of urea as a cost-effective nitrogen source allowed an increase in yeast biomass production. In the second step, a syrup from candied fruit processing, another food waste supplied as carbon feeding, triggered lipid accumulation. Consequently, yeast lipids were produced at a final concentration and productivity of 38 g/L and 0.57 g/L/h respectively, which are among the highest reported values. Through this strategy, based on the valorization of liquid food wastes (WP and mango syrup) and by recovering not only nutritional compounds but also the water necessary for yeast growth and lipid production, we addressed one of the main goals of the circular economy. In addition, we set up an accurate and fast-flow cytometer method to quantify the lipid content, avoiding the extraction step and the use of solvents. This can represent an analytical improvement to screening lipids in different yeast strains and to monitoring the process at the single-cell level. Full article
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18 pages, 1468 KiB  
Article
Sugarcane Bagasse-Based Ethanol Production and Utilization of Its Vinasse for Xylitol Production as an Approach in Integrated Biorefinery
by Sreyden Hor, Mallika Boonmee Kongkeitkajorn and Alissara Reungsang
Fermentation 2022, 8(7), 340; https://doi.org/10.3390/fermentation8070340 - 19 Jul 2022
Cited by 8 | Viewed by 3682
Abstract
Biorefinery of sugarcane bagasse into ethanol and xylitol was investigated in this study. Ethanol fermentation of sugarcane bagasse hydrolysate was carried out by Saccharomyces cerevisiae. After ethanol distillation, the vinasse containing xylose was used to produce xylitol through fermentation by Candida guilliermondii [...] Read more.
Biorefinery of sugarcane bagasse into ethanol and xylitol was investigated in this study. Ethanol fermentation of sugarcane bagasse hydrolysate was carried out by Saccharomyces cerevisiae. After ethanol distillation, the vinasse containing xylose was used to produce xylitol through fermentation by Candida guilliermondii TISTR 5068. During the ethanol fermentation, it was not necessary to supplement a nitrogen source to the hydrolysate. Approximately 50 g/L of bioethanol was produced after 36 h of fermentation. The vinasse was successfully used to produce xylitol. Supplementing the vinasse with 1 g/L of yeast extract improved xylitol production 1.4-fold. Cultivating the yeast with 10% controlled dissolved oxygen resulted in the best xylitol production and yields of 10.2 ± 1.12 g/L and 0.74 ± 0.04 g/g after 60 h fermentation. Supplementing the vinasse with low fraction of molasses to improve xylitol production did not yield a positive result. The supplementation caused decreases of up to 34% in xylitol production rate, 24% in concentration, and 24% in yield. Full article
(This article belongs to the Special Issue Yeast, Biofuels, and Value-Added Products)
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25 pages, 3962 KiB  
Article
Glycerol Utilization as a Sole Carbon Source Disrupts the Membrane Architecture and Solventogenesis in Clostridium beijerinckii NCIMB 8052
by Eric Agyeman-Duah, Santosh Kumar, Bhavana Gangwar and Victor C. Ujor
Fermentation 2022, 8(7), 339; https://doi.org/10.3390/fermentation8070339 - 19 Jul 2022
Cited by 6 | Viewed by 2370
Abstract
Efficient bioconversion of abundant waste glycerol to value-added chemicals calls for a wider range of fermentative workhorses that can catabolize glycerol. In this study, we used quantitative gene expression and solvent profiling, qualitative metabolite analysis, and enzyme activity assays to investigate the factors [...] Read more.
Efficient bioconversion of abundant waste glycerol to value-added chemicals calls for a wider range of fermentative workhorses that can catabolize glycerol. In this study, we used quantitative gene expression and solvent profiling, qualitative metabolite analysis, and enzyme activity assays to investigate the factors that limit glycerol utilization as a sole carbon source by Clostridium beijerinckii NCIMB 8052. C. beijerinckii NCIMB 8052 did not produce acetate, acetone and butanol on glycerol. Congruently, the genes encoding the coenzyme A transferase subunits (ctfAB) and bifunctional acetaldehyde-CoA/alcohol dehydrogenase (adhE) were down-regulated up to 135- and 21-fold, respectively, at 12 h in glycerol-grown cells compared to glucose-grown cells. Conversely, NADH-dependent butanol dehydrogenase A (bdhA) was upregulated 2-fold. Glycerol dehydrogenase (gldA) and dihydroxyacetone kinase (subunit dhaK) were upregulated up to 5- and 881-fold, respectively. Glyceraldehyde-3-phosphate dehydrogenase (gapdh) showed mostly similar expression profiles at 12 h on glucose and glycerol. At 24 h, gapdh was downregulated 1.5-fold, while NADP+-dependent gapdh was upregulated up to 1.9-fold. Glycerol-grown cells showed higher or similar activity profiles for all solventogenic enzymes studied, compared to glucose-grown cells. Butyraldehyde (3 g/L) supplementation led to the production of ~0.1 g/L butanol, whilst butyrate (3.5 g/L) supplementation produced 0.7 and 0.5 g/L acetone and butanol, respectively, with glycerol. Further, the long chain saturated fatty acids cyclopentaneundecanoic acid, methyl ester and hexadecanoic acid, butyl ester were detected in glucose- but not in glycerol-grown cells. Collectively, growth on glycerol appears to disrupt synthesis of saturated long chain fatty acids, as well as solventogenesis in C. beijerinckii NCIMB 8052. Full article
(This article belongs to the Section Microbial Metabolism, Physiology & Genetics)
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11 pages, 1738 KiB  
Article
Microbiota and Mycobiota of Soy Sauce-Supplied Lactic Acid Bacteria Treated with High Pressure
by Chiung-Yu Lai, Chih-Yao Hou, Pei-Ting Chuang, Wei-Hsuan Hsu and She-Ching Wu
Fermentation 2022, 8(7), 338; https://doi.org/10.3390/fermentation8070338 - 18 Jul 2022
Cited by 4 | Viewed by 2651
Abstract
Background: Ethyl carbamate (EC), a byproduct that naturally forms in fermented foods, can cause tumors and cell death and is classified as a probable human carcinogen (Group 2A). EC is naturally formed through the alcoholysis reaction between ethanol and carbamyl compounds. The major [...] Read more.
Background: Ethyl carbamate (EC), a byproduct that naturally forms in fermented foods, can cause tumors and cell death and is classified as a probable human carcinogen (Group 2A). EC is naturally formed through the alcoholysis reaction between ethanol and carbamyl compounds. The major precursors and dominantly emerging stages of EC differ with disparate food types, including soy sauce. This work aimed to clarify the formation of EC and its influence factors throughout the soy sauce production process with or without high-pressure process (HPP) treatment. Methods: Tetragenococcus halophilus, Pediococcus acidilactici, Zygosaccharomyces rouxii, and Candida versatilis were added to soy sauce. The levels of citrulline and EC were measured, and a 16S and ITS assay investigated the microbiota. Results: L-citrulline production was found in each group after fermentation for one month. In addition, L-citrulline levels were generated the most in group D (500 MPa treated raw soy sauce with 12% saltwater and mixed fermentation bacteria, including T. halophilus,P. acidilactici,Z. rouxii, and C. versatilis) and group E (soy sauce fermentation with 12% saltwater without HPP treatment) compared to group F (soy sauce fermentation with 18% saltwater without HPP treatment). Conclusions: These results indicated that salt concentration and mixed fermentation bacteria (T. halophilus,P. acidilactici,Z. rouxii,C. versatilis) might not be major factors for L-citrulline production. Full article
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12 pages, 2181 KiB  
Article
Bioprotective Effect of a Torulaspora delbrueckii/Lachancea thermotolerans-Mixed Inoculum in Red Winemaking
by Rocío Escribano-Viana, Lucía González-Arenzana, Patrocinio Garijo, Laura Fernández, Rosa López, Pilar Santamaría and Ana Rosa Gutiérrez
Fermentation 2022, 8(7), 337; https://doi.org/10.3390/fermentation8070337 - 17 Jul 2022
Cited by 12 | Viewed by 2189
Abstract
One of the alternatives to SO2 as an antimicrobial is the use of bioprotection yeasts, which colonize the medium preventing the proliferation of undesirable microorganisms. In this work, the bioprotective effect of a mixed inoculum formed by Torulaspora delbrueckii/Lachancea thermotolerans [...] Read more.
One of the alternatives to SO2 as an antimicrobial is the use of bioprotection yeasts, which colonize the medium preventing the proliferation of undesirable microorganisms. In this work, the bioprotective effect of a mixed inoculum formed by Torulaspora delbrueckii/Lachancea thermotolerans during fermentation was evaluated. For this purpose, fermentations were carried out using this mixed inoculum and the populations of yeasts, lactic bacteria and acetic bacteria, and the physical–chemical parameters of the wines obtained were studied. The results were compared with those obtained in spontaneous fermentation with and without SO2. The different fermentation strategies caused a differentiation in the yeast species present during fermentation. Regarding populations of lactic acid bacteria, results showed that the effect of the addition of the mixed inoculum was comparable to that exerted by SO2. On the other hand, due to the high sensitivity of acetic acid bacteria to SO2, the sulfite vinifications showed a lower population of acetic acid bacteria in the early stages of fermentation, followed by the vinifications with the mixed inoculum. Full article
(This article belongs to the Special Issue Enological Repercussions of Non-saccharomyces Species 4.0)
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12 pages, 2426 KiB  
Article
Comparative Genome Analysis of Two Heterotrophic Nitrifying Pseudomonas putida Strains Isolated from Freshwater Shrimp Ponds in Soc Trang Province
by Thanh Trung Tran, Nathan J. Bott, Rebecca van Gelderen, Nam Trung Nguyen, Phuong Minh Thi Chu and Ha Hoang Chu
Fermentation 2022, 8(7), 336; https://doi.org/10.3390/fermentation8070336 - 17 Jul 2022
Cited by 1 | Viewed by 1802
Abstract
Nitrogen compounds, especially ammonia, are widely produced in aquaculture systems during cultivation. Ammonia has been investigated as a model compound for use by heterotrophic nitrifying bacteria. Pseudomonas TT321 and Pseudomonas TT322, isolated from shrimp pond water in Soc Trang province, Vietnam, are identified [...] Read more.
Nitrogen compounds, especially ammonia, are widely produced in aquaculture systems during cultivation. Ammonia has been investigated as a model compound for use by heterotrophic nitrifying bacteria. Pseudomonas TT321 and Pseudomonas TT322, isolated from shrimp pond water in Soc Trang province, Vietnam, are identified by comparing them with 31 of the closest genomes sequences from the NCBI nucleotide database. The genome sizes of strains TT321 and TT322 were 5,566,241 bp and 5,563,644 bp, respectively. No plasmids were evident in these strains. Genome analysis revealed that TT321 and TT322 belonged to Pseudomonas putida and shared a common ancestor with 33 genomes. Analysis based on the comparison of genomes showed that three genes, carbamate kinase (arcC), glutamine synthetase (Glul), and aminomethyltransferase (amt), are involved in three metabolic pathways. These pathways are: (i) arginine and proline metabolism, (ii) alanine, aspartate and glutamate metabolism, and (iii) glycine, serine and threonine metabolism. These genes may play important roles in ammonia reduction and support bacterial growth via ammonia assimilation. Full article
(This article belongs to the Section Microbial Metabolism, Physiology & Genetics)
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10 pages, 1998 KiB  
Communication
Increase in Electrical Parameters Using Sucrose in Tomato Waste
by Rojas-Flores Segundo, De La Cruz-Noriega Magaly, Santiago M. Benites, Delfín-Narciso Daniel, Luis Angelats-Silva, Felix Díaz, Cabanillas-Chirinos Luis and Silva-Palacios Fernanda
Fermentation 2022, 8(7), 335; https://doi.org/10.3390/fermentation8070335 - 16 Jul 2022
Cited by 16 | Viewed by 3546
Abstract
The use of organic waste as fuel for energy generation will reduce the great environmental problems currently caused by the consumption of fossil sources, giving agribusiness companies a profitable way to use their waste. In this research, tomato waste with different percentages of [...] Read more.
The use of organic waste as fuel for energy generation will reduce the great environmental problems currently caused by the consumption of fossil sources, giving agribusiness companies a profitable way to use their waste. In this research, tomato waste with different percentages of sucrose (0-target, 5, 10, and 20%) was used in microbial fuel cells manufactured on a laboratory scale with zinc and copper electrodes, managing to generate maximum peaks of voltage and a current of 1.08 V and 6.67 mA in the cell with 20% sucrose, in which it was observed that the optimum operating pH was 5.29, while the MFC with 0% (target) sucrose generated 0.91 V and 3.12 A on day 13 with a similar pH, even though all the cells worked in an acidic pH. Likewise, the cell with 20% sucrose had the lowest internal resistance (0.148541 ± 0.012361 KΩ) and the highest power density (224.77 mW/cm2) at a current density of 4.43 mA/cm2, while the MFC with 0% sucrose generated 160.52 mW/cm2 and 4.38 mA/cm2 of power density and current density, respectively, with an internal resistance of 0.34116 ± 0.2914 KΩ. In this sense, the FTIR (Fourier-transform infrared spectroscopy) of all the substrates used showed a high content of phenolic compounds and carboxylate acids. Finally, the MFCs were connected in a series and managed to generate a voltage of 3.43 V, enough to light an LED (green). These results give great hope to companies and society that, in the near future, this technology can be taken to a larger scale. Full article
(This article belongs to the Collection Food Waste Valorization)
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13 pages, 1860 KiB  
Article
Evaluation and Identification of Key Economic Bottlenecks for Cost-Effective Microbial Oil Production from Fruit and Vegetable Residues
by María Gallego-García, Ana Susmozas, Antonio D. Moreno and María José Negro
Fermentation 2022, 8(7), 334; https://doi.org/10.3390/fermentation8070334 - 15 Jul 2022
Cited by 3 | Viewed by 2654
Abstract
Intensive horticultural systems for the production of vegetables in greenhouses represent one of the main industries generating organic waste, as those that do not meet the quality standards for the fresh market or the processing industry are discarded. This highlights the importance of [...] Read more.
Intensive horticultural systems for the production of vegetables in greenhouses represent one of the main industries generating organic waste, as those that do not meet the quality standards for the fresh market or the processing industry are discarded. This highlights the importance of using these residues as raw material for other applications, such as bioenergy and bioproducts production, within the framework of a bio-based economy that maximizes the utilization of biomass resources in a sustainable manner. In this work, the microbial oil production from discarded pepper using the oleaginous yeast Cryptococcus curvatus was evaluated. Overall, a total lipid accumulation of 16.8 g/L was achieved with a fatty acid profile suitable to produce biodiesel. The lipid yield obtained was 0.12 g/g sugars. In addition, experimental results were used to assess the techno-economic feasibility of a proposed microbial oil plant using the software Aspen Plus. This plant yields approximately 96 kg of microbial oils/ton dry discarded pepper, with an estimated Minimum Selling Price of 7 €·kg−1. These figures point out the necessity of increasing the yield of microbial oil production and considering the utilization of possible by-products, such as mannitol and cell debris, to improve the economic performance of the process. Full article
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16 pages, 3905 KiB  
Article
Shaping an Open Microbiome for Butanol Production through Process Control
by Tiago Pinto, Antonio Grimalt-Alemany, Xavier Flores-Alsina, Hariklia N. Gavala, Krist V. Gernaey and Helena Junicke
Fermentation 2022, 8(7), 333; https://doi.org/10.3390/fermentation8070333 - 15 Jul 2022
Cited by 1 | Viewed by 1730
Abstract
The growing awareness of limited resource availability has driven production systems towards greater efficiencies, and motivated the transition of wastewater treatment plants to water resource recovery facilities. Open microbiome fermentation offers a robust platform for resource recovery, due to its higher metabolic versatility, [...] Read more.
The growing awareness of limited resource availability has driven production systems towards greater efficiencies, and motivated the transition of wastewater treatment plants to water resource recovery facilities. Open microbiome fermentation offers a robust platform for resource recovery, due to its higher metabolic versatility, which is capable of dealing with even dilute residual liquid streams. Organic matter, e.g., fatty acids, lost in these streams can potentially be recovered into higher value chemicals such as alcohols. This study aims to shape an open microbiome towards butanol production from butyrate and hydrogen through pH control and continuous hydrogen supply. Two sets of experiments were conducted in Scott bottles (1 L) and a lab-fermenter (3 L). The open microbiome produced up to 4.4 mM butanol in 1 L bottles. More promising conversions were obtained when up-scaling to a lab-fermenter with pH control and an increased hydrogen partial pressure of 2 bar; results included a butanol concentration of 10.9 mM and an average volumetric productivity of 0.68 mmol L−1 d−1 after 16 days. This corresponds to 2.98- and 4.65-fold increases, respectively, over previously reported values. Thermodynamic calculations revealed that product formation from butyrate was unfeasible, but energetically favorable from bicarbonate present in the inoculum. For the first time, this study provides insights regarding the community structure of an open microbiome producing butanol from butyrate and hydrogen. DNA sequencing combined with 16S rRNA gene amplicon analysis showed high correlation between Mesotoga spp. and butanol formation. Microbial diversity can also explain the formation of by-products from non-butyrate carbon sources. Full article
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7 pages, 1218 KiB  
Communication
Improvements in Human Keratinocytes and Antimicrobial Effect Mediated by Cell-Free Supernatants Derived from Probiotics
by Ji Yeon Lee, YongGyeong Kim, Ja-I Kim, Hyang-Yeol Lee, Gi-Seong Moon and Chang-Ho Kang
Fermentation 2022, 8(7), 332; https://doi.org/10.3390/fermentation8070332 - 15 Jul 2022
Cited by 9 | Viewed by 2470
Abstract
The skin acts as a physical and physiological barrier, thereby protecting the body from various environmental components and stimuli. Cell-free supernatants (CFS) derived from probiotics can improve skin functions and retain moisture. In this study, to assess the efficacy of CFS derived from [...] Read more.
The skin acts as a physical and physiological barrier, thereby protecting the body from various environmental components and stimuli. Cell-free supernatants (CFS) derived from probiotics can improve skin functions and retain moisture. In this study, to assess the efficacy of CFS derived from Ligilactobacillus salivarius and Limosilactobacillus fermentum, we investigated the barrier strengthening and moisturizing effects of CFS in keratinocytes along with their antibacterial effects. We also determined the adhesive effects of probiotics on colorectal cells. To confirm improvements in moisturization and barrier function mediated by CFS in keratinocytes, hyaluronic acid (HA) production, and mRNA expression of HA synthases (HAS)2, HAS3, and FLG were measured. The results showed that CFS from L. salivarius MG242 and L. fermentum MG901 increased the expression of these genes along with the production of HA (2.40- and 1.95-fold of control). Additionally, CFS derived from L. salivarius MG242 and L. fermentum MG901 inhibited the growth of S. aureus and E. coli, thereby demonstrating inhibitory effects against harmful pathogens observed on the skin. These results indicate that the use of CFS derived from L. salivarius MG242 and L. fermentum MG901 may increase moisturization in the skin and improve barrier function of keratinocytes along with elimination of potential pathogens. Full article
(This article belongs to the Special Issue Postbiotics from Production to Their Health-Promoting Aspects)
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18 pages, 2157 KiB  
Review
Yeasts as Producers of Flavor Precursors during Cocoa Bean Fermentation and Their Relevance as Starter Cultures: A Review
by Hugo Gabriel Gutiérrez-Ríos, Mirna Leonor Suárez-Quiroz, Zorba Josué Hernández-Estrada, Olaya Pirene Castellanos-Onorio, Rodrigo Alonso-Villegas, Patricia Rayas-Duarte, Cynthia Cano-Sarmiento, Claudia Yuritzi Figueroa-Hernández and Oscar González-Rios
Fermentation 2022, 8(7), 331; https://doi.org/10.3390/fermentation8070331 - 14 Jul 2022
Cited by 17 | Viewed by 13153
Abstract
During the fermentation of cocoa beans, the yeasts produce volatile organic compounds (VOCs). Through reactions associated with amino acid metabolism, yeasts generate important aroma precursors as acetate esters and fatty acid ethyl esters are essential in developing fruity flavors and aromas in the [...] Read more.
During the fermentation of cocoa beans, the yeasts produce volatile organic compounds (VOCs). Through reactions associated with amino acid metabolism, yeasts generate important aroma precursors as acetate esters and fatty acid ethyl esters are essential in developing fruity flavors and aromas in the final product (usually chocolate). In addition, some yeasts may have pectinolytic and antifungal activity, which is desirable in the post-harvest process of cocoa. The main yeast species in cocoa fermentation are Saccharomyces cerevisiae, Pichia kudriavzevii, and Hanseniaspora opuntiae. These produce higher alcohols and acetyl-CoA to make acetate–esters, compounds that produce floral and fruity notes. However, there are still controversies in scientific reports because some mention that there are no significant differences in the sensory characteristics of the final product. Others mention that the fermentation of cocoa by yeast has a significant influence on improving the sensory attributes of the final product. However, using yeasts as starter cultures for cocoa bean fermentation is recommended to homogenize sensory attributes such as notes and flavors in chocolate. Full article
(This article belongs to the Special Issue Yeast Aroma)
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10 pages, 2686 KiB  
Article
Enhancement of the Antihypertensive Effect of Fermented Sargassum horneri with Lactiplantibacillus pentosus SN001
by Momoko Tamura, Satoshi Shimizu, Hiroshi Nagai, Orie Yoshinari and Naoko Hamada-Sato
Fermentation 2022, 8(7), 330; https://doi.org/10.3390/fermentation8070330 - 14 Jul 2022
Cited by 6 | Viewed by 2014
Abstract
Sargassum horneri is a seaweed with antihypertensive properties. However, it is underutilized in some areas, and effective utilization methods are being sought. In this study, we prepared a fermented S. horneri using lactic acid bacteria Lactiplantibacillus pentosus SN001 and investigated its effective utilization [...] Read more.
Sargassum horneri is a seaweed with antihypertensive properties. However, it is underutilized in some areas, and effective utilization methods are being sought. In this study, we prepared a fermented S. horneri using lactic acid bacteria Lactiplantibacillus pentosus SN001 and investigated its effective utilization by enhancing its antihypertensive effect. The ACE inhibitory activity of S. horneri ranged from 3.6% to a maximum of 63.3% after fermentation. In vivo studies using mice and spontaneously hypertensive rats (SHR) suggested an antihypertensive effect of fermented S. horneri. Purification and NMR analysis of the ACE inhibitory component in fermented S. horneri identified glycerol. Therefore, it is suggested that glycerol is responsible for the strong antihypertensive effect of fermented S. horneri. In conclusion, S. horneri is expected to be used as a dietary ingredient with enhanced antihypertensive effect by fermentation with L. pentosus SN001. Full article
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15 pages, 1320 KiB  
Article
Rumen Bacteria Abundance and Fermentation Profile during Subacute Ruminal Acidosis and Its Modulation by Aspergillus oryzae Culture in RUSITEC System
by Tongqing Guo, Tao Guo, Long Guo, Fei Li, Fadi Li and Zhiyuan Ma
Fermentation 2022, 8(7), 329; https://doi.org/10.3390/fermentation8070329 - 14 Jul 2022
Cited by 7 | Viewed by 1781
Abstract
This study aimed at characterizing changes in rumen bacteria abundance and fermentation profiles by artificial saliva (AS) pH, and at evaluating the potential modulatory role of Aspergillus oryzae culture (AOC) in a rumen simulation technique (RUSITEC) system. The treatment included high AS pH [...] Read more.
This study aimed at characterizing changes in rumen bacteria abundance and fermentation profiles by artificial saliva (AS) pH, and at evaluating the potential modulatory role of Aspergillus oryzae culture (AOC) in a rumen simulation technique (RUSITEC) system. The treatment included high AS pH (pH 6.8) or low AS pH (pH 5.5) according to the McDougall’s method, and low AS pH was sustained by changing the composition of the AS (NaHCO3 from 9.8 to 1.96 g/L, Na2HPO4 from 9.3 to 1.86 g/L). In low AS pH condition, the diets contained either 0% AOC, 1.25% AOC, or 2.5% AOC. Therefore, there are four treatments: (1) high AS pH, 0% AOC (HASP); (2) low AS pH, 0% AOC (AOC0); (3) low AS pH, 1.25% AOC (AOC1); (4) low AS pH, 2.5% AOC (AOC2), respectively. The experimental diets were supplemented with 16 g basic diets with the forage to concentrate ratio of 40:60. The experiments were conducted two independent 13 days, with 9 days adaption periods and 4 days sample collection. The results showed that low AS pH decreased the degradabilites of dry matter (DM), organic matter (OM), crude protein (CP), neutral detergent fiber (NDF), and acid detergent fiber (ADF) (p < 0.05), which occurred due to a decreased abundance of fibrolytic Ruminococcus albus (p < 0.001). The total concentration of volatile fatty acid (VFA) and proportion of propionate were decreased in the low AS pH (p = 0.026) and tended to increase the molar proportion of butyrate (p = 0.086) and the ratio of acetate to propionate (p = 0.088). The abundances of phylum Firmicutes (p = 0.065) and Proteobacteria (p = 0.063) tended to be greater in low AS pH group than high AS pH group. Low AS pH increased the abundance of phylum Actinobacteria (p = 0.002) compared to the high AS pH and decreased the abundances of phylum Spirochaetes (p = 0.032). Compared with the high AS pH, low AS pH increased the abundances of Prevotella (p = 0.003), Pseudoscardovia (p = 0.001), Mitsuokella (p = 0.005), and Dialister (p = 0.047), and decreased the abundances of Olivibacter (p = 0.026), Ruminobacter (p = 0.025), Treponema (p = 0.037), and Sphaerochaeta (p = 0.027) at genus level. Under a severe SARA in RUSITEC, supplementation of 2.5% AOC increased OM degradability, the copy numbers of Selenomonas ruminantium and Fibrobacter succinogenes. These findings indicate that the reduction AS pH at 5.5 caused a strong shift in bacterial composition in rumen. In addition, the addition of AOC in diets increased the growth rate of certain rumen bacteria that digest fiber or utilize lactate under SARA condition in RUSITEC system. Full article
(This article belongs to the Special Issue In Vitro Fermentation)
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15 pages, 2527 KiB  
Article
Probiotic and Antioxidant Potential of the Lactobacillus Spp. Isolated from Artisanal Fermented Pickles
by Urva Akmal, Ifra Ghori, Abdelbaset Mohamed Elasbali, Bandar Alharbi, Arshad Farid, Abdulhakeem S. Alamri, Muhammad Muzammal, Syed Mohammed Basheeruddin Asdaq, Mohammed A. E. Naiel and Shakira Ghazanfar
Fermentation 2022, 8(7), 328; https://doi.org/10.3390/fermentation8070328 - 13 Jul 2022
Cited by 13 | Viewed by 4370
Abstract
The present study was based on bacterial isolation with probiotic potential from artisanal fermented pickles. A total of 36 bacterial strains were isolated from 50 different artisanal fermented pickle samples. Nine isolates with promising probiotic potential (PCR99, PCR100, PCR118, PCR119, PCR121, PCR125, PCR137, [...] Read more.
The present study was based on bacterial isolation with probiotic potential from artisanal fermented pickles. A total of 36 bacterial strains were isolated from 50 different artisanal fermented pickle samples. Nine isolates with promising probiotic potential (PCR99, PCR100, PCR118, PCR119, PCR121, PCR125, PCR137, PCR140 and PCR141) were selected. The strains showed varied protease, amylase, lipase and cellulase patterns. The isolated strains displayed varied responses towards various antibiotic classes, i.e., PCR140 showed resistance to penicillin G, polymyxin B, Metronidazole and Streptomycin. PCR140 showed highest resistance to bile salt concentrations (0.3% and 0.5%) and acidic conditions (pH 3 and pH 4) when exposed to mimicked gastrointestinal conditions. The cell viability against enzymes produced in stomach and intestines showed different patterns as pepsin was in the range of 94.32–91.22%, pancreatic resistance 97.32–93.11% and lysozyme resistance was detected at 99.12–92.55%. Furthermore, the auto-aggregation capability of isolated strains was in the range of 46.11–33.33% and cell surface hydrophobicity was in the range of 36.55–31.33%. PCR 140 showed maximum antioxidant activity in lyophilized cells as well as probiotic potential. A phylogenetic analysis based on 16S rRNA gene sequencing confirmed that PCR140 (NMCC91) with higher in vitro probiotic and antioxidant potential belongs to the genus Lactobacillus with 97% similarity with Lacticaseibacillus paracasei. This work demonstrated that the isolate PCR 140 (NMCC91) is suitable for use in food and medical industries. Full article
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12 pages, 1572 KiB  
Article
Occurrence of Toxic Biogenic Amines in Various Types of Soft and Hard Cheeses and Their Control by Bacillus polymyxa D05-1
by Marwa A. Saad, Hagar S. Abd-Rabou, Ebrahim Elkhtab, Ahmed M. Rayan, Ahmed Abdeen, Afaf Abdelkader, Samah F. Ibrahim and Heba Hussien
Fermentation 2022, 8(7), 327; https://doi.org/10.3390/fermentation8070327 - 13 Jul 2022
Cited by 7 | Viewed by 3018
Abstract
Egyptian cheeses are considered an important part of the Egyptian diet. This study aimed to examine 60 random samples of different types of commercial cheeses in Egypt, including soft cheeses (Domiati and Tallaga) and hard cheeses (Cheddar and Ras). The samples were subjected [...] Read more.
Egyptian cheeses are considered an important part of the Egyptian diet. This study aimed to examine 60 random samples of different types of commercial cheeses in Egypt, including soft cheeses (Domiati and Tallaga) and hard cheeses (Cheddar and Ras). The samples were subjected to chemical and microbial examination. Biogenic amines (BAs) are nitrogenous compounds found in a variety of foods; their presence is undesirable and related to spoilage, and can result in toxicological effects in humans. Thus, BAs were determined by using a high-performance liquid chromatography (HPLC) analysis. Moreover, the ability of Bacillus polymyxa D05-1 to reduce levels of experimentally added biogenic amines during the manufacturing of Tallaga cheese was investigated. The obtained results revealed variations in the chemical composition between the investigated samples. Furthermore, many cheese samples contained high levels of BAs, including histamine, tyramine and putrescine. Domiati cheese had the highest levels of BAs, followed by Tallaga and Cheddar, whereas Ras cheese had the lowest levels. The existence of yeasts, molds, coliforms and the high levels of BAs in cheese samples indicate the unsanitary conditions in which they were made and stored. Furthermore, addition of B. polymyxa D05-1 during Tallaga cheese manufacturing resulted in a reduction in BA levels. Full article
(This article belongs to the Special Issue Assessment of the Quality and Safety of Fermented Foods)
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15 pages, 535 KiB  
Article
Enhancement of Antioxidant Activities in Black Soy Milk through Isoflavone Aglycone Production during Indigenous Lactic Acid Bacteria Fermentation
by Benediktus Yudo Leksono, Muhammad Nur Cahyanto, Endang Sutriswati Rahayu, Rini Yanti and Tyas Utami
Fermentation 2022, 8(7), 326; https://doi.org/10.3390/fermentation8070326 - 13 Jul 2022
Cited by 9 | Viewed by 2534
Abstract
Black soybeans contain high antioxidant compounds such as isoflavone but mainly in glucoside form, with low antioxidant activities. Fermentation by lactic acid bacteria (LAB) can enhance the antioxidant properties, but its ability is strain-dependent. This study aims to study the ability of Indonesian [...] Read more.
Black soybeans contain high antioxidant compounds such as isoflavone but mainly in glucoside form, with low antioxidant activities. Fermentation by lactic acid bacteria (LAB) can enhance the antioxidant properties, but its ability is strain-dependent. This study aims to study the ability of Indonesian indigenous LAB, Lactiplantibacillus plantarum WGK 4, Streptococcus thermophilus Dad 11, and Lactiplantibacillus plantarum Dad 13, to enhance the antioxidant properties during black soy milk fermentation. Fermentation was carried out at 37 °C for 24 h. Viable cell, acid production, Folin–Ciocalteu assay, antioxidant activity (DPPH), isoflavone aglycone daidzein and genistein, and β-glucosidase activity were measured every six hours. All LAB strains could grow well during the fermentation of black soy milk. Lactiplantibacillus plantarum WGK 4 produced the highest acid (1.50%). All three LAB strains could enhance antioxidant activity (DPPH) from 24.90% to 31.22–38.20%, followed by increased isoflavone aglycone. All strains could increase daidzein and genistein content, ranging from 61% to 107% and 81% to 132%, respectively. All three Indonesian indigenous LAB enhanced antioxidant properties of black soy milk relatively at the same level and potentially could be used as a starter culture of black soy milk fermentation. Full article
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39 pages, 2296 KiB  
Review
Intensification of Acidogenic Fermentation for the Production of Biohydrogen and Volatile Fatty Acids—A Perspective
by Sanjay Nagarajan, Rhys Jon Jones, Lucy Oram, Jaime Massanet-Nicolau and Alan Guwy
Fermentation 2022, 8(7), 325; https://doi.org/10.3390/fermentation8070325 - 11 Jul 2022
Cited by 20 | Viewed by 6082
Abstract
Utilising ‘wastes’ as ‘resources’ is key to a circular economy. While there are multiple routes to waste valorisation, anaerobic digestion (AD)—a biochemical means to breakdown organic wastes in the absence of oxygen—is favoured due to its capacity to handle a variety of feedstocks. [...] Read more.
Utilising ‘wastes’ as ‘resources’ is key to a circular economy. While there are multiple routes to waste valorisation, anaerobic digestion (AD)—a biochemical means to breakdown organic wastes in the absence of oxygen—is favoured due to its capacity to handle a variety of feedstocks. Traditional AD focuses on the production of biogas and fertiliser as products; however, such low-value products combined with longer residence times and slow kinetics have paved the way to explore alternative product platforms. The intermediate steps in conventional AD—acidogenesis and acetogenesis—have the capability to produce biohydrogen and volatile fatty acids (VFA) which are gaining increased attention due to the higher energy density (than biogas) and higher market value, respectively. This review hence focusses specifically on the production of biohydrogen and VFAs from organic wastes. With the revived interest in these products, a critical analysis of recent literature is needed to establish the current status. Therefore, intensification strategies in this area involving three main streams: substrate pre-treatment, digestion parameters and product recovery are discussed in detail based on literature reported in the last decade. The techno-economic aspects and future pointers are clearly highlighted to drive research forward in relevant areas. Full article
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14 pages, 923 KiB  
Article
Wine Microbial Consortium: Seasonal Sources and Vectors Linking Vineyard and Winery Environments
by Sofia Camilo, Mahesh Chandra, Patrícia Branco and Manuel Malfeito-Ferreira
Fermentation 2022, 8(7), 324; https://doi.org/10.3390/fermentation8070324 - 11 Jul 2022
Cited by 10 | Viewed by 2063
Abstract
Winemaking involves a wide diversity of microorganisms with different roles in the process. The wine microbial consortium (WMC) includes yeasts, lactic acid bacteria and acetic acid bacteria with different implications regarding wine quality. Despite this technological importance, their origin, prevalence, and routes of [...] Read more.
Winemaking involves a wide diversity of microorganisms with different roles in the process. The wine microbial consortium (WMC) includes yeasts, lactic acid bacteria and acetic acid bacteria with different implications regarding wine quality. Despite this technological importance, their origin, prevalence, and routes of dissemination from the environment into the winery have not yet been fully unraveled. Therefore, this study aimed to evaluate the WMC diversity and incidence associated with vineyard environments to understand how wine microorganisms overwinter and enter the winery during harvest. Soils, tree and vine barks, insects, vine leaves, grapes, grape musts, and winery equipment were sampled along four seasons. The isolation protocol included: (a) culture-dependent microbial recovery; (b) phenotypical screening to select fermenting yeasts, lactic acid, and acetic acid bacteria; and (c) molecular identification. The results showed that during all seasons, only 11.4% of the 1424 isolates presumably belonged to the WMC. The increase in WMC recovery along the year was mostly due to an increase in the number of sampled sources. Acetic acid bacteria (Acetobacter spp., Gluconobacter spp., Gluconoacetobacter spp.) were mostly recovered from soils during winter while spoilage lactic acid bacteria (Leuconostoc mesenteroides and Lactobacillus kunkeii) were only recovered from insects during véraison and harvest. The fermenting yeast Saccharomyces cerevisiae was only isolated from fermented juice and winery equipment. The spoilage yeast Zygosaccharomyces bailii was only recovered from fermented juice. The single species bridging both vineyard and winery environments was the yeast Hanseniaspora uvarum, isolated from insects, rot grapes and grape juice during harvest. Therefore, this species appears to be the best surrogate to study the dissemination of the WMC from vineyard into the winery. Moreover, the obtained results do not evidence the hypothesis of a perennial terroir-dependent WMC given the scarcity of their constituents in the vineyard environment along the year and the importance of insect dissemination. Full article
(This article belongs to the Special Issue New Aspect on Wine Fermentation)
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11 pages, 729 KiB  
Review
Chondroitin Sulfate and Its Derivatives: A Review of Microbial and Other Production Methods
by Adeola E. Awofiranye, Jon Hudson, Aditi Dey Tithi, Robert J. Linhardt, Wanwipa Vongsangnak and Mattheos A. G. Koffas
Fermentation 2022, 8(7), 323; https://doi.org/10.3390/fermentation8070323 - 10 Jul 2022
Cited by 11 | Viewed by 5737
Abstract
Chondroitin sulfate (CS) is widely used across the world as a nutraceutical and pharmaceutical. Its high demand and potential limitations in current methods of extraction call for an alternative method of production. This review highlights glycosaminoglycan’s structure, its medical significance, animal extraction source, [...] Read more.
Chondroitin sulfate (CS) is widely used across the world as a nutraceutical and pharmaceutical. Its high demand and potential limitations in current methods of extraction call for an alternative method of production. This review highlights glycosaminoglycan’s structure, its medical significance, animal extraction source, and the disadvantages of the extraction process. We cover alternative production strategies for CS and its precursor, chondroitin. We highlight chemical synthesis, chemoenzymatic synthesis, and extensively discuss how strains have been successfully metabolically engineered to synthesize chondroitin and chondroitin sulfate. We present microbial engineering as the best option for modern chondroitin and CS production. We also explore the biosynthetic pathway for chondroitin production in multiple microbes such as Escherichia coli, Bacillus subtilis, and Corynebacterium glutamicum. Lastly, we outline how the manipulation of pathway genes has led to the biosynthesis of chondroitin derivatives. Full article
(This article belongs to the Special Issue Production of Pharmaceuticals and Nutraceuticals by Fermentation)
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13 pages, 2110 KiB  
Article
Investigating the Evolution of Structural Characteristics of Humic Acid Generated during the Continuous Anaerobic Digestion and Its Potential for Chromium Adsorption and Reduction
by Xiqing Wang, Pengjiao Tian, Atif Muhmood, Juan Liu, Yingjie Su, Qianqian Zhang, Yi Zheng and Renjie Dong
Fermentation 2022, 8(7), 322; https://doi.org/10.3390/fermentation8070322 - 10 Jul 2022
Cited by 7 | Viewed by 1934
Abstract
Humic acid (HA), as an important by-product, has been demonstrated to affect anaerobic digestion performance and subsequent land application of digestate via the batch anaerobic digestion process. However, the knowledge about the evolution of structure and function of HA during continuous anaerobic digestion [...] Read more.
Humic acid (HA), as an important by-product, has been demonstrated to affect anaerobic digestion performance and subsequent land application of digestate via the batch anaerobic digestion process. However, the knowledge about the evolution of structure and function of HA during continuous anaerobic digestion (AD) is still unclear. Therefore, the current study examined the structural changes in HA produced during the continuous AD process and its metal-adsorption-reduction abilities. The results of three-dimensional fluorescence spectroscopy showed a general upsurge in humic-like components’ abundance (70–77%), with an increase in humification index (2.56–3.43). Likewise, the content of HA increased from 4.8 g L−1 to 6.9 g L−1 in the continuous AD process. The evolution of C-H, O-H, C=O, C=C, and C-O functional groups of HA was observed via the 2D COS FTIR analysis. Moreover, the concurrent dynamics of functional groups contributed to the higher adsorption (255.2 mg g−1) of Cr (VI) and reduction (60.3 mg g−1) of Cr (VI) to Cr (III) after 168 days of the continuous AD process. The findings of the current study not only advanced understanding of the evolution of HA during continuous anaerobic digestion and its metal remediation potential but also support further research toward developing an eco-friendly and innovative strategy for the remediation of heavy metals contaminated soils employing anaerobic digestate as an auxiliary agent. Full article
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12 pages, 2422 KiB  
Article
Production of Gamma-Aminobutyric Acid by Levilactobacillus brevis CD0817 by Coupling Fermentation with Self-Buffered Whole-Cell Catalysis
by Haixing Li, Tianyi Sun, Mengya Jia, Lingqin Wang, Cheng Wei, Jinfeng Pei, Zhiyu Lin and Shuixing Wang
Fermentation 2022, 8(7), 321; https://doi.org/10.3390/fermentation8070321 - 9 Jul 2022
Cited by 12 | Viewed by 2661
Abstract
There is a recent trend of using lactic acid bacteria for the production of gamma-aminobutyric acid (GABA). This study described a method that combines fermentation and self-buffered whole-cell catalysis for the efficient production of GABA using Levilactobacillus brevis CD0817. Upon the completion of [...] Read more.
There is a recent trend of using lactic acid bacteria for the production of gamma-aminobutyric acid (GABA). This study described a method that combines fermentation and self-buffered whole-cell catalysis for the efficient production of GABA using Levilactobacillus brevis CD0817. Upon the completion of GABA fermentation, cells were recovered to conduct whole-cell catalysis by which the substrate L-glutamic acid was catalytically decarboxylated to GABA. L-glutamic acid itself maintained the acidity essential for decarboxylation. To maximize the whole-cell catalysis ability, the effects of the cell culture method, catalysis temperature, catalysis time, cell concentration, and L-glutamic acid dosage were investigated. The results illustrate that the cells that were cultivated for 16 h in a fermentation medium supplemented with 20.0 g/L of glucose were the most suitable for the whole-cell catalytic production of GABA. At 16 h, the fermentative GABA content reached 204.2 g/L. Under optimized whole-cell catalytic conditions (temperature 45.0 °C, time 12.0 h, wet cells 25.0 g/L, and L-glutamic acid 120.0 g/L), 85.1 g/L of GABA was obtained, with 3.7 ± 0.9 g/L of substrate residue. GABA was recovered from the system by sequentially performing rotary vacuum evaporation, precipitation with ethanol, filtration with filter paper, and drying. The purity of the GABA product reached 97.1%, with a recovery rate of 87.0%. These data suggest that the proposed method has potential applications in the production of GABA. Full article
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14 pages, 2343 KiB  
Article
Effects of Lactic Acid Bacteria-Inoculated Corn Silage on Bacterial Communities and Metabolites of Digestive Tract of Sheep
by Hongyan Han, Chao Wang, Zhipeng Huang, Ying Zhang, Lin Sun, Yanlin Xue and Xusheng Guo
Fermentation 2022, 8(7), 320; https://doi.org/10.3390/fermentation8070320 - 8 Jul 2022
Cited by 6 | Viewed by 2687
Abstract
Silage is widely used as ruminant feed all over the world. Lactic acid bacteria inoculants are commonly applied in silage production to improve preservation efficiency. To investigate the effects of lactic acid bacteria-inoculated silage on the bacterial communities and metabolites of the digestive [...] Read more.
Silage is widely used as ruminant feed all over the world. Lactic acid bacteria inoculants are commonly applied in silage production to improve preservation efficiency. To investigate the effects of lactic acid bacteria-inoculated silage on the bacterial communities and metabolites of the digestive tract, twenty-four local hybrid rams (a hybrid of Small Tail Han sheep and Mongolian sheep with an average initial BW 27.8 ± 3.05 kg) were randomly divided into four groups fed with corn stalk (S), corn stalk silage, corn stalk silage treated with Lentilactobacillusplantarum (P), or corn stalk silage treated with L. buchneri (B). The results showed that compared with the control and B groups, the inoculant with P significantly increased silage dry matter (DM) content, while the pH value was significantly higher than that in group B, and the aerobic stability was significantly lower than that in group B. Firmicutes and Bacteroidetes were the two dominant phyla of digestive tract microbiota in sheep. Compared with corn stalk, sheep fed with corn stalk silage showed a higher relative abundance of Prevotella. P-treated silage decreased the relative abundance of Firmicutes at the phylum level in rumen fluid. Silage treated with P or B increased the relative abundance of Prevotella, Ruminococcus, and Fibrobacter at the genus level in the rumen. A total of 498 differential metabolites in the rumen were detected when comparing the corn stalk and corn stalk silage groups. A total of 257 and 141 differential metabolites were detected when comparing the untreated silage and silages treated with P and B, respectively. These metabolites in the sheep rumen were correlated with bacterial communities, especially Butyrivibrio, Fibrobacter, and Prevotella. In conclusion, the addition of P and B during ensiling could change the fermentation and metabolites in the rumen by influencing the bacterial community. The change induced by these inoculants might be beneficial for animals’ performance and the health of ruminants. Full article
(This article belongs to the Section Microbial Metabolism, Physiology & Genetics)
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6 pages, 224 KiB  
Editorial
Biofuels Production and Processing Technology
by Alessia Tropea
Fermentation 2022, 8(7), 319; https://doi.org/10.3390/fermentation8070319 - 7 Jul 2022
Cited by 11 | Viewed by 4918
Abstract
The negative global warming impact and global environmental pollution due to fossil fuels mean that the main challenge of modern society is finding alternatives to conventional fuels. In this scenario, biofuels derived from renewable biomass represent the most promising renewable energy sources. Depending [...] Read more.
The negative global warming impact and global environmental pollution due to fossil fuels mean that the main challenge of modern society is finding alternatives to conventional fuels. In this scenario, biofuels derived from renewable biomass represent the most promising renewable energy sources. Depending on the biomass used by the fermentation technologies, it is possible obtain first-generation biofuels produced from food crops, second-generation biofuels produced from non-food feedstock, mainly starting from renewable lignocellulosic biomasses, and third-generation biofuels, represented by algae or food waste biomass. Although biofuels appear to be the closest alternative to fossil fuels, it is necessary for them to be produced in competitive quantities and costs, requiring both improvements to production technologies and diversification of feedstock. This Special Issue is focused on technological innovations, which include but are not limited to the utilization of different feedstock; different biomass pretreatments; fermentation strategies, such as simultaneous saccharification and fermentation (SSF) or separate hydrolysis and fermentation (SHF); different applied microorganisms used as monoculture or co-culture; and different setups for biofuel fermentation processes. Full article
(This article belongs to the Special Issue Biofuels Production and Processing Technology)
11 pages, 255 KiB  
Review
The Impact of Vineyard Mechanization on Grape and Wine Phenolics, Aroma Compounds, and Sensory Properties
by Qun Sun, Craig Ebersole, Deborah Parker Wong and Karley Curtis
Fermentation 2022, 8(7), 318; https://doi.org/10.3390/fermentation8070318 - 6 Jul 2022
Cited by 3 | Viewed by 2970
Abstract
Grapes are one of the most valuable fruit crops in the United States and can be processed into a variety of products. The grape and wine industry contributes to and impacts the U.S. agricultural economy. However, rising labor costs and global competition pose [...] Read more.
Grapes are one of the most valuable fruit crops in the United States and can be processed into a variety of products. The grape and wine industry contributes to and impacts the U.S. agricultural economy. However, rising labor costs and global competition pose challenges for the grape and wine industry. Vineyard mechanization is a promising strategy to increase efficiency and address the labor shortage and cost issues. Recent studies have focused on the impact of vineyard mechanization on general grape and wine quality. Wine phenolics, aroma compounds, and sensory characteristics are the key indicators of wine quality and consumer preference. This article aims to review the impact of vineyard mechanization, specifically mechanical harvesting, mechanical leaf removal, mechanical shoot thinning, cluster thinning, and mechanical pruning on grape and wine phenolics, and aroma compounds and sensory profile. Studies have shown that vineyard mechanization significantly affects phenolic and aroma compounds, especially grape-derived aroma compounds such as volatile thiols, terpenes, C13-norpentadiene, and methoxypyrazine. Mechanically processed grapes can produce wines of the same or better quality than wines made from hand-operated grapes. Vineyard mechanization could be a promising strategy for grape growers to reduce operating costs and maintain or improve grape and wine quality. Future research directions in the area of vineyard mechanization were discussed. It provides a comprehensive view and information on the topic to both grape growers and winemakers in the application of vineyard mechanization. Full article
(This article belongs to the Special Issue Wine Aromas)
16 pages, 3676 KiB  
Article
Physicochemical, Functional, and Technological Properties of Protein Hydrolysates Obtained by Microbial Fermentation of Broiler Chicken Gizzards
by Oksana Zinina, Svetlana Merenkova, Maksim Rebezov, Damir Galimov, Mars Khayrullin and Pavel Burkov
Fermentation 2022, 8(7), 317; https://doi.org/10.3390/fermentation8070317 - 6 Jul 2022
Cited by 9 | Viewed by 2337
Abstract
Fermentation is an economical method for obtaining protein hydrolysates. The purpose of the scientific research was to perform a comprehensive analysis of the physicochemical, technological, and functional properties of protein hydrolysates obtained by microbial fermentation. The research results showed that hydrolysates fermented with [...] Read more.
Fermentation is an economical method for obtaining protein hydrolysates. The purpose of the scientific research was to perform a comprehensive analysis of the physicochemical, technological, and functional properties of protein hydrolysates obtained by microbial fermentation. The research results showed that hydrolysates fermented with propionic acid bacteria and bifidobacteria have better physicochemical and technological indicators compared to the control sample. Significant increases in water-holding and fat-holding capacities (by 1.8–2.1 times and 1.5–2.5 times, respectively), as well as fat-emulsifying ability (by 12.8–29.8%) in experimental samples were found. Hydrolysates obtained by fermentation effectively inhibit the growth of Escherichia coli and Staphylococcus aureus. The thermal analysis showed a sufficiently high-thermal stability of the obtained protein hydrolysates. In hydrolysates fermented by bacterial culture, the removal of physico-mechanical and osmotically bound moisture occurred at temperatures of 110 °C and 115 °C, respectively, and in whey protein hydrolysate at a temperature of 100 °C. The release of chemically bound moisture was observed at a temperature of 170 °C for fermented hydrolysates and at 155 °C for the control sample. The results proved that fermented protein products are characterized by high functional properties, antioxidant and antimicrobial activity, and can be used as natural food additives and preservatives. Full article
(This article belongs to the Special Issue Assessment of the Quality and Safety of Fermented Foods)
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29 pages, 2128 KiB  
Review
The Potential of Marine Microalgae for the Production of Food, Feed, and Fuel (3F)
by Chandan Mahata, Probir Das, Shoyeb Khan, Mahmoud I. A. Thaher, Mohammed Abdul Quadir, Senthil Nagappan Annamalai and Hareb Al Jabri
Fermentation 2022, 8(7), 316; https://doi.org/10.3390/fermentation8070316 - 5 Jul 2022
Cited by 26 | Viewed by 7657
Abstract
Whole-cell microalgae biomass and their specific metabolites are excellent sources of renewable and alternative feedstock for various products. In most cases, the content and quality of whole-cell biomass or specific microalgal metabolites could be produced by both fresh and marine microalgae strains. However, [...] Read more.
Whole-cell microalgae biomass and their specific metabolites are excellent sources of renewable and alternative feedstock for various products. In most cases, the content and quality of whole-cell biomass or specific microalgal metabolites could be produced by both fresh and marine microalgae strains. However, a large water footprint for freshwater microalgae strain is a big concern, especially if the biomass is intended for non-food applications. Therefore, if any marine microalgae could produce biomass of desired quality, it would have a competitive edge over freshwater microalgae. Apart from biofuels, recently, microalgal biomass has gained considerable attention as food ingredients for both humans and animals and feedstock for different bulk chemicals. In this regard, several technologies are being developed to utilize marine microalgae in the production of food, feed, and biofuels. Nevertheless, the production of suitable and cheap biomass feedstock using marine microalgae has faced several challenges associated with cultivation and downstream processing. This review will explore the potential pathways, associated challenges, and future directions of developing marine microalgae biomass-based food, feed, and fuels (3F). Full article
(This article belongs to the Special Issue Marine-Based Biorefinery: A Path Forward to a Sustainable Future)
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13 pages, 928 KiB  
Article
Starch Properties, Nutrients Profiles, In Vitro Ruminal Fermentation and Molecular Structure of Corn Processed in Different Ways
by Chengxing Han, Yanli Guo, Xiaofang Cai and Ruixing Yang
Fermentation 2022, 8(7), 315; https://doi.org/10.3390/fermentation8070315 - 3 Jul 2022
Cited by 9 | Viewed by 2990
Abstract
Processing will improve the digestion of corn by ruminant animals. The objectives of this study were to investigate the effects of processing methods (grinding, G; steam flaking, SF; extrusion, E) on the starch properties, nutrient profiles, in vitro ruminal fermentation and molecular structure [...] Read more.
Processing will improve the digestion of corn by ruminant animals. The objectives of this study were to investigate the effects of processing methods (grinding, G; steam flaking, SF; extrusion, E) on the starch properties, nutrient profiles, in vitro ruminal fermentation and molecular structure of corn. Compared with G, SF and E increased (p < 0.05) the starch content, starch gelatinization, ruminal gas production (GP, 0.5–32 h), propionic acid, starch degradability (SD), the area and height of carbohydrate peaks, and decreased (p < 0.05) starch crystallinity, content of crude protein, neutral detergent fiber and acid detergent fiber, ruminal NH3-N, the area and height of amide I and II, α-helix, and β-sheet. The total VFA (24 h, 48 h) tended to be increased by SF and E (p < 0.10). The carbohydrate peak area and height were positively (p < 0.05) correlated with GP (1–24 h) and SD. The protein molecular absorption intensity was negatively correlated with SD (p < 0.05). The change in starch properties, GP (1–24 h) and molecular structure caused by E was greater than SF (p < 0.05). These results indicated that the higher starch gelatinization and lower starch crystallinity of E corn, induced by the high temperature and pressure, enabled more fermentation and digestion in the artificial rumen. The carbohydrate and protein molecular structures were correlated with the nutritional characteristics of corn. Full article
(This article belongs to the Special Issue In Vitro Fermentation)
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