Fermentation

21 pages, 886 KiB

Open AccessArticle

Machine Learning Prediction of Foaming in Anaerobic Co-Digestion from Six Key Process Parameters

by Sarah E. Daly and Ji-Qin Ni

Fermentation 2024, 10(12), 639; https://doi.org/10.3390/fermentation10120639 - 13 Dec 2024

Foaming in co-digested anaerobic digesters can reduce biogas production, leading to economic loss. However, the underlying causes of foaming are not completely understood. This study investigated a field-scale mesophilic digester system that experienced intermittent foaming, employing experimental and modeling methods over a 16-month [...] Read more.

Foaming in co-digested anaerobic digesters can reduce biogas production, leading to economic loss. However, the underlying causes of foaming are not completely understood. This study investigated a field-scale mesophilic digester system that experienced intermittent foaming, employing experimental and modeling methods over a 16-month period. Samples were collected during both foaming and non-foaming events and were thoroughly characterized for methane (CH₄) yields and different physical and chemical concentrations, including volatile solids (VS), metals, total phosphorus (TP), total chemical oxygen demand (TCOD), total volatile fatty acids (TVFAs), and total alkalinity (TALK). Machine learning techniques were applied to predict foaming events with several algorithms tested to optimize prediction accuracy. The results showed that digester liquid and effluent samples collected from foaming events had significantly lower (p < 0.05) average CH₄ yields (77 and 45 mL CH₄ g VS⁻¹) than during non-foaming events (150 and 83 mL CH₄ g VS⁻¹). Recursive feature modeling identified six key parameters (1. Fe(II):S; 2. Fe(II):TP; 3. TCOD; 4. Fe; 5. TVFA:TALK; and 6. Cu) associated with digester foaming. Among the tested machine learning models, the support vector machine (SVM) algorithm achieved the highest recognition accuracy of 87%. This study demonstrates that the interactions of multiple chemical and physical process parameters are an important consideration for predicting anaerobic digester foaming. Full article

(This article belongs to the Section Fermentation Process Design)

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27 pages, 3299 KiB

Open AccessReview

Advances in Biotechnological Strategies for Sustainable Production of Non-Animal Proteins: Challenges, Innovations, and Applications

by Emanuel do Nascimento Muniz, Rebeca Teixeira de Queiroz Montenegro, Daniel Nascimento da Silva, Alan Portal D’Almeida, Luciana Rocha Barros Gonçalves and Tiago Lima de Albuquerque

Fermentation 2024, 10(12), 638; https://doi.org/10.3390/fermentation10120638 - 13 Dec 2024

Abstract

This review explores recent advances in the design of fermentation processes for producing alternative proteins, focusing on utilizing agro-industrial waste and renewable substrates. New bioprocess strategies, such as experimental designs, optimizing bioreactors, bioprocesses, and applying precision fermentation can improve the protein yields and [...] Read more.

This review explores recent advances in the design of fermentation processes for producing alternative proteins, focusing on utilizing agro-industrial waste and renewable substrates. New bioprocess strategies, such as experimental designs, optimizing bioreactors, bioprocesses, and applying precision fermentation can improve the protein yields and nutritional value. Also, unconventional substrates, such as hydrolysates derived from agro-industrial residues conversion may result in cost reduction and enhanced feasibility. The application of enzymes to produce protein-rich foods with high bioaccessibility that improve digestibility and nutritional value are also highlighted. This article addresses the importance of developing cost-effective fermentation solutions that minimize the environmental impact while addressing technical challenges such as scalability and contamination control. Furthermore, it emphasizes the growing need for innovations in fermentation process design to ensure the sustainability of industrial protein production. The review concludes that improvements in process design are fundamental in overcoming technological and regulatory barriers, particularly in increasing the efficiency and competitiveness of non-meat proteins in the global market. Full article

(This article belongs to the Special Issue Research on Microbial Protein Synthesis: 2nd Edition)

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14 pages, 1107 KiB

Open AccessArticle

Effect of Nitrite and Temperature on Autotrophic Denitrification in Anammox Granular Biomass from a Partial Nitritation–Anammox Reactor

by Benjamín Ibarra, Yves Lesty, Mateo Pastur, Celia Castro, Chloe Girard and Rolando Chamy

Fermentation 2024, 10(12), 637; https://doi.org/10.3390/fermentation10120637 - 12 Dec 2024

Abstract

Anaerobic ammonium oxidation (anammox) is a key process in the removal of nitrogen from wastewater, in which episodes of substrate inhibition may occur. In this study, the effect of nitrite on anammox in the short and long term was investigated using granules from [...] Read more.

Anaerobic ammonium oxidation (anammox) is a key process in the removal of nitrogen from wastewater, in which episodes of substrate inhibition may occur. In this study, the effect of nitrite on anammox in the short and long term was investigated using granules from a full-scale SBR reactor in operation. In the short term, maximum activity was achieved at 100 mg N-NO₂⁻/L, with higher concentrations being inhibitory. It was determined that the biomass behavior is well interpreted (R² = 0.955) by a non-competitive substrate inhibition model (Andrews model), with a K_S of 55.6 mg N-NO₂⁻/L and a K_I of 116.7 mg N-NO₂⁻/L, and also well interpreted by the Edwards model (R² = 0.957), with a K_S of 36 mg N-NO₂⁻/L and a K_I of 287 mg N-NO₂⁻/L. In the long term, the biomass retained its anammox activity at 15 mg N-NO₂⁻/L over a three TRH horizon; however, at 30 mg N-NO₂⁻/L, anammox activity decreased by 50% at the end of the experiment. Finally, the effect of temperature on the activity of the anammox granules from a different source was studied, revealing that the activity increases with temperature within the range of 25–35 °C, which can be useful if a rapid increase in activity is desired. Operationally, maintaining nitrite below 30 mg N-NO₂⁻/L ensures stability, while exceeding 100 mg N-NO₂⁻/L causes immediate SAA inhibition and slower recovery. Full article

(This article belongs to the Special Issue Treatment of Municipal Wastewater by Anaerobic Biotechnology)

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3 pages, 181 KiB

Open AccessEditorial

Advances in Research on Beverages, Food, Yeast and Brewing

by Ogueri Nwaiwu

Fermentation 2024, 10(12), 636; https://doi.org/10.3390/fermentation10120636 - 12 Dec 2024

Abstract

This closing Editorial marks the end of three volumes of this Special Issue (SI), which covered themes like changes in reactants and products, chemistry, sensory properties, microbiology, transcriptomics, proteomics and metabolomics, food safety, and nutrition [...] Full article

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

11 pages, 1208 KiB

Open AccessArticle

Development of High-Glucosinolate-Retaining Lactic-Acid-Bacteria-Co-Fermented Cabbage Products

by Chen-Che Hsieh, Yuan-Heng Liu, Shin-Ping Lin, Shella Permatasari Santoso, Kaemwich Jantama, Tsung-Yu Tsai, Chang-Wei Hsieh and Kuan-Chen Cheng

Fermentation 2024, 10(12), 635; https://doi.org/10.3390/fermentation10120635 - 12 Dec 2024

Abstract

Cabbage (Brassica oleracea var. capitata) is rich in dietary fiber, vitamins, trace elements, and functional components like glucosinolates, which are essential for promoting health. This study aims to enhance the health benefits and nutritional content of cabbage through lactic acid fermentation [...] Read more.

Cabbage (Brassica oleracea var. capitata) is rich in dietary fiber, vitamins, trace elements, and functional components like glucosinolates, which are essential for promoting health. This study aims to enhance the health benefits and nutritional content of cabbage through lactic acid fermentation using a bioreactor, with a particular focus on glucosinolate retention. The fermentation utilized a consortium of Lactiplantibacillus plantarum, known for its robust acidifying capabilities, and antioxidant-rich strains Lactobacillus acidophilus and Bifidobacterium longum. A 5 L bioreactor facilitated the controlled fermentation process (35 °C, 24 h of fermentation at 5 rpm). The efficacy of glucosinolate retention was quantitatively assessed alongside the analysis of antioxidant properties via 1,1-diphenyl-2-picrylhydrazil (DPPH) and 2,2′-Azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) assays. The results indicated a notable enhancement in antioxidant capacity with a 16.32% increase in the DPPH radical scavenging rate compared to non-fermented cabbage. Glucosinolate retention was impressively sustained at 82.02% in bioreactor conditions. Storage stability tests conducted at 4 °C revealed minimal degradation of glucosinolates, maintaining significant levels up to 14 days (from 90.34% to 66.49%). This study underscores the potential of bioreactor-facilitated lactic acid fermentation in preserving and enhancing the nutritional and functional qualities of cabbage, thereby extending its market value and promoting sustainable agricultural practices. Full article

(This article belongs to the Special Issue Application of Lactic Acid Bacteria in Fermented Food: 2nd Edition)

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16 pages, 2528 KiB

Open AccessArticle

Continuous Production of Chitin Oligosaccharides Utilizing an Optimized Enzyme Production-Adsorption-Enzymolysis-Product Separation (EAES) System

by Xiuling Zhou, Yang Huang, Yuying Liu, Delong Pan and Yang Zhang

Fermentation 2024, 10(12), 634; https://doi.org/10.3390/fermentation10120634 - 12 Dec 2024

Abstract

Chitin oligosaccharide (CHOS) is a chitin derivative with excellent biological activities. Enzymatic hydrolysis of chitin-rich biomass into CHOS is a hot topic in research on the high-value utilization of chitin resources. The disadvantages of complex preparation and purification processes and the high cost [...] Read more.

Chitin oligosaccharide (CHOS) is a chitin derivative with excellent biological activities. Enzymatic hydrolysis of chitin-rich biomass into CHOS is a hot topic in research on the high-value utilization of chitin resources. The disadvantages of complex preparation and purification processes and the high cost of chitin-degrading enzymes limit large-scale enzymatic production and application of CHOS. In this study, the activity of chitinase increased from 1.8 U/mL to 3.52 U/mL by 94.4% after optimizing the carbon and nitrogen source of Chitiniphilus sp. LZ32 fermentation. An enzyme production-adsorption-enzymolysis-product separation (EAES) system was constructed using fermentation, an adsorption purification module, and a product ultrafiltration module of a chitin-degrading enzyme. CHOS production by continuous enzymatic hydrolysis was performed in an EAES system using housefly larval powder (HLP) as the substrate. After the C. sp. LZ32 fermentation broth was circulated in the adsorption module for 90 min, the adsorption rate of the chitin-degrading enzyme reached more than 90%. The ultrafiltration module effectively separated CHOS at an operating pressure of 2 bar. Four batches of CHOS were produced in the EAES system using repeated batch fermentation. The running time of a single batch decreased from 115 h in the first batch to 48 h, and the CHOS output of each batch gradually increased. The total CHOS output was 61 g, and the production efficiency was 0.24 g/h. The CHOS produced by the EAES system (ECHOS) has high antioxidant activity. In this study, the EAES system was used to simplify the purification and separation steps of CHOS preparation, and the continuous production of CHOS was realized, which has potential application prospects in the field of green CHOS production. Full article

(This article belongs to the Special Issue Metabolic Engineering in Microbial Synthesis)

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14 pages, 297 KiB

Open AccessReview

Innovations in Limnospira platensis Fermentation: From Process Enhancements to Biotechnological Applications

by Maria P. Spínola, Ana R. Mendes and José A. M. Prates

Fermentation 2024, 10(12), 633; https://doi.org/10.3390/fermentation10120633 - 11 Dec 2024

Abstract

The cyanobacterium Limnospira platensis, vulgarly Spirulina, has gained significant attention due to its high protein content, rich bioactive compounds, and health benefits, making it a valuable resource in biotechnology, nutraceuticals, food supplements, biopharmaceuticals, and cosmetics. Recent advancements in fermentation technology have considerably [...] Read more.

The cyanobacterium Limnospira platensis, vulgarly Spirulina, has gained significant attention due to its high protein content, rich bioactive compounds, and health benefits, making it a valuable resource in biotechnology, nutraceuticals, food supplements, biopharmaceuticals, and cosmetics. Recent advancements in fermentation technology have considerably improved the efficiency, scalability, and cost-effectiveness of L. platensis production while addressing environmental sustainability and enhancing product quality. Based on well-recognized databases (Google Scholar, PubMed, Scopus, Web of Science), this review explores the latest developments in L. platensis fermentation, emphasizing strain improvement, bioprocess engineering, and optimization of fermentation parameters. It also examines key factors such as bioreactor design, downstream processing, and innovative monitoring technologies aimed at maximizing biomass yield and bioactive compound production. Additionally, emerging applications of fermented L. platensis in various industries and future perspectives, including large-scale production, regulatory barriers, and biosafety considerations, are discussed. These insights provide a comprehensive outlook on the future of L. platensis fermentation in biotechnological applications. Full article

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

14 pages, 3391 KiB

Open AccessArticle

Comparative Study on Selenium and Volatile Compounds in Selenium-Enriched Cardamine violifolia Pickles Fermented by Three Distinct Methods

by Jue Gong, Shen Rao, Xiaomeng Liu, Shuiyuan Cheng, Xin Cong and Dingxiang Zhu

Fermentation 2024, 10(12), 632; https://doi.org/10.3390/fermentation10120632 - 11 Dec 2024

Abstract

Cardamine violifolia is a selenium (Se)-rich vegetable crop belonging to the Brassicaceae family. This study investigated the Se concentration and volatiles in the fresh (CK) C. violifolia, natural fermented (NF), Lactiplantibacillus plantarum (LP), and Leuconostoc mesenteroides (LM) fermented C. violifolia pickles. Results [...] Read more.

Cardamine violifolia is a selenium (Se)-rich vegetable crop belonging to the Brassicaceae family. This study investigated the Se concentration and volatiles in the fresh (CK) C. violifolia, natural fermented (NF), Lactiplantibacillus plantarum (LP), and Leuconostoc mesenteroides (LM) fermented C. violifolia pickles. Results showed that fermentation promoted the levels of selenocysteine, methyl selenocysteine, and selenate. A total of 648 volatile compounds were found, including 119 terpenoids, 105 heterocyclic compounds, 103 esters, and 65 hydrocarbons. Differential analysis of volatiles indicated that fermentation induced the release of volatiles when compared to CK, whereas volatile profiles in LM and NF pickles showed notable differences from LP pickles. SeCys2, MeSeCys, and selenate significantly correlated to several volatile compounds, implying that Se metabolism may affect the formation of volatiles. Conclusively, fermentation promoted the release of aroma and bioactive volatiles and the degradation of unpleasant and harmful substances in C. violifolia pickles. Full article

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

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15 pages, 2627 KiB

Open AccessArticle

Wine Yeast Strains Under Ethanol-Induced Stress: Morphological and Physiological Responses

by Elisa Aiello, Mattia Pia Arena, Luciana De Vero, Carlo Montanini, Michele Bianchi, Andrea Mescola, Andrea Alessandrini, Andrea Pulvirenti and Maria Gullo

Fermentation 2024, 10(12), 631; https://doi.org/10.3390/fermentation10120631 - 11 Dec 2024

Abstract

During alcoholic fermentation, ethanol accumulation significantly impacts yeast cells by disrupting membrane integrity, increasing permeability, and reducing cell viability. This study evaluated the effects of ethanol stress on the growth, membrane fluidity, and cell surface morphology of Saccharomyces cerevisiae and non-Saccharomyces yeast [...] Read more.

During alcoholic fermentation, ethanol accumulation significantly impacts yeast cells by disrupting membrane integrity, increasing permeability, and reducing cell viability. This study evaluated the effects of ethanol stress on the growth, membrane fluidity, and cell surface morphology of Saccharomyces cerevisiae and non-Saccharomyces yeast strains, specifically Torulaspora delbrueckii and Metschnikowia pulcherrima. These strains, commercialized by AEB SpA and preserved at the Unimore Microbial Culture Collection (UMCC), were tested for fermentative performance in grape must and grown under varying ethanol concentrations. Membrane fluidity was measured using Laurdan generalized polarization (GP), while Atomic Force Microscopy (AFM) assessed cell surface morphology. Results indicated that at 10% ethanol, membrane fluidity increased, particularly in strains able to tolerate up to 16% ethanol, which also demonstrated superior fermentative performance. Less tolerant strains, such as T. delbrueckii UMCC 5 and M. pulcherrima UMCC 15, showed smaller increases in fluidity. At 18% ethanol, these strains exhibited severely altered surface morphology and larger surface roughness values, suggesting increased instability under high ethanol stress, while more tolerant strains displayed better-preserved surface morphology and lower roughness values, reflecting enhanced adaptability. These findings offer insights into yeast responses to ethanol stress, supporting the development of more resilient strains for improved fermentation. Full article

(This article belongs to the Special Issue Innovative Strategies for the Management of Wine Fermentations: 2nd Edition)

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Graphical abstract

19 pages, 1666 KiB

Open AccessArticle

Intake of Condensed Tannins (Acacia mearnsii) by Lambs in Confinement and Its Impact on Growth Performance, Rumen Environment, and Meat

by Andrei L. R. Brunetto, Ana Luiza F. dos Santos, Isadora Zago, Guilherme L. Deolino, Luisa Nora, Vitor L. Molosse, Rafael V. P. Lago, Aline de C. Machado, Roger Wagner, Jelson N. Nauderer, Bianca F. Bissacotti, Aniela P. Kempka, Bruna Klein and Aleksandro S. Da Silva

Fermentation 2024, 10(12), 630; https://doi.org/10.3390/fermentation10120630 - 10 Dec 2024

Abstract

This study determined whether adding condensed tannins to the diet of confined lamb improves performance, metabolism, health, and meat composition and quality. We used 24 Lacaune lambs with an average initial weight of 24.5 ± 0.24 kg. The animals were divided into 12 [...] Read more.

This study determined whether adding condensed tannins to the diet of confined lamb improves performance, metabolism, health, and meat composition and quality. We used 24 Lacaune lambs with an average initial weight of 24.5 ± 0.24 kg. The animals were divided into 12 pens with two animals each. In the treatment group, a black wattle extract was added to the lamb concentrate (2.5 g/kg dry matter), while the control group received only the basal diet (without extract). Black wattle contained 98.6 g/kg of condensed tannin. There was no difference between the performance variables, which included weight gain, feed intake, and feed efficiency. However, the group fed on condensed tannins showed higher carcass yield and a higher percentage of linked intramuscular fat. In meat, a lower proportion of saturated fatty acids combined with higher concentrations of unsaturated fatty acids was observed in lambs of the condensed tannin group. The polyunsaturated fatty acids (PUFA) were no different; however, a higher PUFA/SFA ratio was observed in animals with condensed tannin intake, and a higher proportion of ω6 and ω3 was observed in the meat of these animals. The meat’s protein and ash content did not differ between treatments, as did the meat’s water retention capacity, color, and luminosity. Furthermore, animals that fed on condensed tannins had lower cholesterol levels and higher globulin content. The values of erythrogram variables were lower in lambs that consumed condensed tannins. More significant ruminal bacterial activity was also observed in the group receiving condensed tannins. The antioxidant effect was verified with lower thiobarbituric acid reactive species (TBARS) levels and more significant antioxidant enzyme activity. We conclude that adding condensed tannins improves carcass yield and increases the percentage of fat in the carcass, improving the fatty acid profile, which may be linked to the antioxidant effect, in addition to the health benefits of the consumer of this product. Full article

(This article belongs to the Special Issue Fermentation Technologies for the Production of High-Quality Feed)

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14 pages, 3725 KiB

Open AccessArticle

Metagenomic Insights into the Bacterial Diversity of Balinese Fermented Sausage (Urutan) from the Household Industry

by Ida Bagus Agung Yogeswara, Ni Wayan Nursini, I Gusti Ayu Wita Kusumawati and Purwaningtyas Kusumaningsih

Fermentation 2024, 10(12), 629; https://doi.org/10.3390/fermentation10120629 - 10 Dec 2024

Abstract

Fermented urutan is a dry fermented sausage made from a mixture of pork and Balinese spices, traditionally prepared using conventional methods. However, variations in spices and raw materials may affect the bacterial diversity of urutan. This study aimed to reveal the bacterial [...] Read more.

Fermented urutan is a dry fermented sausage made from a mixture of pork and Balinese spices, traditionally prepared using conventional methods. However, variations in spices and raw materials may affect the bacterial diversity of urutan. This study aimed to reveal the bacterial diversity of urutan from household industries using a metagenomic approach. A bacterial diversity analysis was conducted using Nanopore Sequencing Technology (ONT). Samples were collected from household industries in two regencies: Tabanan and Gianyar. The results show that Bacillota (98%) had the highest abundance in all samples at the phylum level. At the genus level, variations in bacterial composition were observed, with Staphylococcus (8–89%), Weissella (5–32%), and Lactococcus (3–39%) being the most abundant. The richness and diversity of bacterial species were greater in the KH group (Gianyar regency) than in the BRT group (Tabanan regency). A correlation analysis revealed that five genera—Staphylococcus, Lactococcus, Mammalicoccus, Macrococcoides, and Citrobacter—showed a strong correlation with the pH, water activity (aW), and acidity of fermented urutan. These findings provide insights into the bacterial community and could aid in the development of starter cultures to improve the consistency and quality of traditional fermented foods. Full article

(This article belongs to the Special Issue Applied Microorganisms and Industrial/Food Enzymes, 2nd Edition)

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24 pages, 8453 KiB

Open AccessArticle

Assessment of Characteristic Flavor and Taste Quality of Sugarcane Wine Fermented with Different Cultivars of Sugarcane

by Yuxia Yang, Jing Chen, Fengjin Zheng, Bo Lin, Feifei Wu, Krishan K. Verma and Ganlin Chen

Fermentation 2024, 10(12), 628; https://doi.org/10.3390/fermentation10120628 - 9 Dec 2024

Abstract

In order to explore the variation in volatile compounds and aroma profiles of different varieties of sugarcane wine, volatile compounds of 14 different varieties of sugarcane wine were analyzed by headspace solid-phase microextraction–gas chromatography–mass spectrometry (HS-SPME-GC-MS) and an electronic sensory system. The differences [...] Read more.

In order to explore the variation in volatile compounds and aroma profiles of different varieties of sugarcane wine, volatile compounds of 14 different varieties of sugarcane wine were analyzed by headspace solid-phase microextraction–gas chromatography–mass spectrometry (HS-SPME-GC-MS) and an electronic sensory system. The differences in flavor substances of different cultivars of sugarcane were assessed by orthogonal partial least squares discriminant analysis (OPLS-DA) discriminant model and relative odor activity value (ROAV) combined with multivariate statistical methods. The results showed that a total of sixty major volatile compounds, i.e., 27 esters, 15 alcohols, eight acids, three phenols, four aldehydes and ketones, and four others, were identified in 14 types of sugarcane wine. Seven key aroma compounds were screened out: ethyl caprylate, ethyl caprate, ethyl acetate, ethyl laurate, n-decanoic acid, 2,4-di-tert-butylphenol, and 2-phenylethanol and three differential aromas, i.e., ethyl palmitate, isobutyl alcohol, and caprylic acid. The electronic nose and electronic tongue analysis technology can effectively distinguish the aroma and taste of 14 sugarcane wines. It is confirmed that the aroma and taste of 14 sugarcane wines have differences in distribution patterns, and the results are consistent with the analysis and assessment of volatile compounds of sugarcane wine. The results of this study provide technical support for the production and quality improvement of sugarcane wine. Full article

(This article belongs to the Special Issue Progress in Wine Fermentation and Aging)

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14 pages, 3447 KiB

Open AccessArticle

Enhancement of the Degradation of Phytosterol Side Chains in Mycolicibacterium by Eliminating the Redox Sensitivity of Key Thiolase and Augmenting Cell Activity

by Xiuling Zhou, Yuying Liu, Fuyi Li, Yang Huang, Hongzhuan Xuan and Yang Zhang

Fermentation 2024, 10(12), 627; https://doi.org/10.3390/fermentation10120627 - 8 Dec 2024

Abstract

Androstenedione (AD) is a vital intermediate in the synthesis of steroid drugs, making its efficient production critical in the steroid drug industry. Acetyl-CoA acetyltransferase (FadA5), a thiolase enzyme, plays an important role in the metabolic process of degrading phytosterol side chains in Mycolicibacterium [...] Read more.

Androstenedione (AD) is a vital intermediate in the synthesis of steroid drugs, making its efficient production critical in the steroid drug industry. Acetyl-CoA acetyltransferase (FadA5), a thiolase enzyme, plays an important role in the metabolic process of degrading phytosterol side chains in Mycolicibacterium to produce AD. This work is the first systematic analysis of the role of FadA5 in the transformation of phytosterols by Mycolicibacterium to produce AD. The relationship between redox potential and AD production was examined using resting cells, and it was confirmed that FadA5 is a key enzyme for AD production. Mutating the 87th cysteine of FadA5 to alanine reduced its redox effect, enhancing the substrate tolerance and biotransformation capacity of the strain. Co-expressing Vitreoscilla hemoglobin (VHb) and propionyl-CoA metabolized the transcription activator (PrpR), decreased intracellular reactive oxygen species levels, and improved cell viability. The AD yield of MSP-fA5C87A-VP/ΔfA5 was 2.541 g/L, an increase of 16.83% over the control strain. Using a repeated batch fermentation process, the production efficiency of the MSP-fA5C87A-VP/ΔfA5 strain was 0.658 g/L/d, which was 1.82 times higher than that of the control strain. These findings provide a theoretical basis for understanding and regulating steroid side-chain catabolism in Mycolicibacterium and offer support for the rational modification of industrial strains for steroidal drug precursor production. Full article

(This article belongs to the Special Issue Fermentation-Driven Biological Structural Modification of Natural Products)

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13 pages, 1893 KiB

Open AccessArticle

Cellulose Nanofibers as Rheological Modifiers to Improve Biomass Slurry Processing and Fermentation

by Zachary Jamieson, Jordi Francis Clar and Troy Runge

Fermentation 2024, 10(12), 626; https://doi.org/10.3390/fermentation10120626 - 8 Dec 2024

Abstract

This study investigates the enhancement of biomass slurry processability through the addition of rheological modifiers, focusing on carboxymethyl cellulose (CMC) and TEMPO-mediated oxidized cellulose nanofibrils (TCNF). Three sets of experiments were conducted to assess the effects of these additives on slurry processing and [...] Read more.

This study investigates the enhancement of biomass slurry processability through the addition of rheological modifiers, focusing on carboxymethyl cellulose (CMC) and TEMPO-mediated oxidized cellulose nanofibrils (TCNF). Three sets of experiments were conducted to assess the effects of these additives on slurry processing and fermentation. Initial experiments evaluated the slurry extrudability, concluding that TCNF aids extrusion similarly to CMC. Subsequent experiments explored slurry viscosity reduction mechanisms, revealing that while CMC significantly reduced the viscosity, TCNF’s impact is negligible. Additionally, TCNF performed comparably to CMC in water retention tests across different conditions, which suggests that TCNF have potential as an effective additive for maintaining slurry fluidity at high solid concentrations through enhanced water retention. Lastly, both additives were investigated to ensure that they did not impact hydrolyzed biomass fermentation. The findings suggest that TCNF’s mechanisms differ from those of traditional water-soluble polymers like CMC, offering insights into novel approaches to improve the biomass processing efficiency and subsequent fermentation. Full article

(This article belongs to the Special Issue Lignocellulosic Biomass Valorization)

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16 pages, 2790 KiB

Open AccessSystematic Review

The Use of Mesquite Pods (Prosopis spp.) as an Alternative to Improve the Productive Performance and Methane Mitigation in Small Ruminants: A Meta-Analysis

by Juan Carlos Angeles-Hernandez, Ever del Jesús Flores Santiago, Eduardo Cardoso-Gutiérrez, Sara S. Valencia-Salazar, Oscar Enrique del Razo Rodriguez, Erwin A. Paz, Juan C. Ku-Vera, Ermias Kebreab, Mohammed Benaouda and Ángel Garduño García

Fermentation 2024, 10(12), 625; https://doi.org/10.3390/fermentation10120625 - 7 Dec 2024

Abstract

Mesquite (Prosopis spp.), a highly nutritious legume from arid regions characterized by its secondary metabolites, offers a cost-effective resource to provide energy and protein for small ruminant farmers in harsh environments. In addition, the high concentrations of secondary metabolites found in mesquite [...] Read more.

Mesquite (Prosopis spp.), a highly nutritious legume from arid regions characterized by its secondary metabolites, offers a cost-effective resource to provide energy and protein for small ruminant farmers in harsh environments. In addition, the high concentrations of secondary metabolites found in mesquite pods could be an option to mitigate methane (CH₄) emissions. Thus, the aim of this study was to conduct an analytical review to assess the impact of adding mesquite pods on small ruminant productivity and enteric CH₄ emissions. A comprehensive and structured search of scientific articles resulted in a database of 38 trials. The response variables were evaluated through raw mean differences (RMDs) and standardized mean differences (SMDs), followed by a meta-regression, used to investigate the heterogeneity of the explanatory variables. Supplementation with mesquite pods significantly increased the dry matter intake (DMI) and average daily gain (ADG) and reduced the feed conversion ratio (FCR), with sheep showing the highest effect. The meta-regression demonstrated that the mesquite pod effect was influenced mainly by the species, level of incorporation and processing of the pods. Studies employing in silico CH₄ estimation reported increased emissions when the diets included mesquite pods. In contrast, in vivo studies demonstrated promising results, showing a significant reduction in CH₄ emissions when mesquite pods were included in small ruminant diets. Therefore, future research should focus on evaluating mesquite pod supplementation using precise methods to assess CH₄ emissions. Full article

(This article belongs to the Special Issue Ruminal Fermentation)

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16 pages, 983 KiB

Open AccessArticle

Synergetic Effect of Accentuated Cut Edges (ACE) and Macerating Enzymes on Aroma and Sensory Profiles of Marquette Red Wine

by Yiliang Cheng and Aude A. Watrelot

Fermentation 2024, 10(12), 624; https://doi.org/10.3390/fermentation10120624 - 6 Dec 2024

Abstract

This research explored the effects of using Accentuated Cut Edges (ACE) and macerating enzymes on the aroma and sensory profile of Marquette red wines after nine months of aging. The aroma analysis was conducted using gas chromatography-mass spectrometry (GC-MS) with solid-phase microextraction (SPME). [...] Read more.

This research explored the effects of using Accentuated Cut Edges (ACE) and macerating enzymes on the aroma and sensory profile of Marquette red wines after nine months of aging. The aroma analysis was conducted using gas chromatography-mass spectrometry (GC-MS) with solid-phase microextraction (SPME). The intensity of basic sensory attributes, including color, aroma, taste, and mouthfeel, were evaluated by eight trained panelists through descriptive analysis using 15 cm line scales. ACE treatment affected the aroma compounds profile, as suggested by the increased response ratio of ethyl butanoate, ethyl 2-methylpropanoate, and ethyl 3-methylbutanoate. Statistically, it significantly intensified honey (by 1.6 times) and green apple (by 2.1 times) notes, as perceived by panelists, compared to the control during the sensory descriptive analysis. Regardless of the type of enzymes, combined ACE and enzymes treatment amplified the color intensity of wine by up to 71.4% as observed by panelists, though this was not captured by spectrophotometric measurements (p > 0.05) from the previous study. A lower concentration of ester-derived compounds was found in ACE with enzymes wines, which was associated with the lower intensity of fruity notes during the descriptive analysis. Notably, none of the treatments affected astringency perception, likely due to the low concentration and small molecular weight of condensed tannins, alongside changes in the composition of soluble polysaccharide in Marquette red wines. Full article

(This article belongs to the Special Issue Science and Technology of Winemaking)

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13 pages, 3252 KiB

Open AccessArticle

Scaling up Trickle Bed Reactor for Gas Fermentation Technology: The Effect of Temperature and Reactor Characteristics on Mass Transfer

by Sambit Dutta, Hariklia N. Gavala and Ioannis V. Skiadas

Fermentation 2024, 10(12), 623; https://doi.org/10.3390/fermentation10120623 - 6 Dec 2024

Abstract

The increasing demand for efficient and sustainable industrial processes has accelerated research into green alternatives. Gas fermentation in a trickle bed reactor is a promising technology; however, optimal scaling up is still challenging. A mass transfer model is crucial for identifying bottlenecks and [...] Read more.

The increasing demand for efficient and sustainable industrial processes has accelerated research into green alternatives. Gas fermentation in a trickle bed reactor is a promising technology; however, optimal scaling up is still challenging. A mass transfer model is crucial for identifying bottlenecks and suggesting design improvements to optimize the scale-up of TBR for gas fermentation. This study explores the effects of temperature, reactor dimensions, and packing material size on the volumetric mass transfer coefficient (k_La) in a commercial-scale trickle bed reactor (TBR). Using dynamic mass transfer modeling, the research results highlight that thermophilic conditions (60 °C) significantly enhance k_La and mass transfer rates for H₂, CO, and CO₂, despite reduced gas solubility at higher temperatures. Additionally, packing material of smaller particles improves k_La by increasing the surface for gas–liquid interaction, while reactor dimensions, particularly volume and diameter, are shown to critically influence k_La. This study provides valuable insights into optimizing TBR design and scale-up, emphasizing the importance of thermophilic conditions, proper packing material selection, and reactor geometry for efficient gas–liquid mass transfer in syngas (a mixture of H₂, CO, and CO₂) biological conversion. Overall, the findings offer practical guidelines for enhancing the performance of industrial-scale TBR systems. Full article

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

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2 pages, 163 KiB

Open AccessCorrection

Correction: Wang et al. Antibacterial Efficacy of Feline-Derived Lactic Acid Bacteria against Enteropathogenic Escherichia coli: A Comprehensive In Vitro Analysis. Fermentation 2024, 10, 514

by Weiwei Wang, Hao Dong, Qianqian Chen, Xiaohan Chang, Longjiao Wang, Chengyi Miao, Shuxing Chen, Lishui Chen, Ran Wang, Shaoyang Ge and Wei Xiong

Fermentation 2024, 10(12), 622; https://doi.org/10.3390/fermentation10120622 - 6 Dec 2024

Abstract

Some paragraphs were missing from the original publication [...] Full article

(This article belongs to the Special Issue Antimicrobial Metabolites: Production, Analysis and Application)

14 pages, 1904 KiB

Open AccessArticle

Mixed Strains of Bacillus velezensis PBS-17, Lactiplantibacillus plantarum J-135, and Saccharomyces cerevisiae DAE-4 Increase the Storage Capacity of Fermented Feed and Silage

by Eun-Jae Park, Moon Joo Kim, Bori Lee, Hyun-Jae Jang and Seung Woong Lee

Fermentation 2024, 10(12), 621; https://doi.org/10.3390/fermentation10120621 - 5 Dec 2024

Abstract

In this study, we investigated whether three microbial strains, Lactiplantibacillus plantarum J-135, Saccharomyces cerevisiae DAE-4, and Bacillus velezensis PBS-17, could be used to reduce mold growth and spoilage during the production of fermented feed. These microorganisms were isolated and characterized via an evaluation [...] Read more.

In this study, we investigated whether three microbial strains, Lactiplantibacillus plantarum J-135, Saccharomyces cerevisiae DAE-4, and Bacillus velezensis PBS-17, could be used to reduce mold growth and spoilage during the production of fermented feed. These microorganisms were isolated and characterized via an evaluation of their antibacterial activity, enzymatic activity, bile acid resistance, and acid tolerance. L. plantarum J-135 and S. cerevisiae DAE-4 demonstrated excellent acid tolerance and bile acid resistance, and L. plantarum J-135 exhibited antibacterial activity against Salmonella species. B. velezensis PBS-17 showed the greatest protease, cellulase, α-amylase, and phytase enzymatic activities, and displayed antibacterial activity against Fusarium solani, Aspergillus flavus, Penicillium sp., and Fusarium oxysporum. The three isolated strains were diluted to the same concentration (1:1:1) to create a culture solution, which was added to a standard feed (experimental group) to prepare fermented feed. This was compared with feed treated with a commercially available single probiotic preparation (control group 1) or a mixed microbial preparation that was composed of multiple strains, including B. subtilis. The feed treated with the single probiotic preparation spoiled after 21 days due to insufficient lactic acid bacteria growth, whereas the feed treated with the mixed microbial preparation exhibited mold growth after 14 days. The bacteria and fungi that cause spoilage during fermented feed production were effectively controlled in feed treated with L. plantarum J-135, S. cerevisiae DAE-4, and B. velezensis PBS-17. Therefore, the mixture of these three microbial strains may reduce the risk of spoilage during fermented silage and feed processing, thereby improving storage properties and stability. Full article

(This article belongs to the Section Industrial Fermentation)

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