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Journal Description

Fermentation

Fermentation is an international, peer-reviewed, open access journal on fermentation process and technology published monthly online by MDPI.

Open Access— free for readers, with article processing charges (APC) paid by authors or their institutions.
High Visibility: indexed within Scopus, SCIE (Web of Science), PubAg, FSTA, Inspec, CAPlus / SciFinder, and other databases.
Journal Rank: JCR - Q2 (Biotechnology and Applied Microbiology) / CiteScore - Q1 (Plant Science)
Rapid Publication: manuscripts are peer-reviewed and a first decision is provided to authors approximately 15.5 days after submission; acceptance to publication is undertaken in 3.9 days (median values for papers published in this journal in the first half of 2025).
Recognition of Reviewers: reviewers who provide timely, thorough peer-review reports receive vouchers entitling them to a discount on the APC of their next publication in any MDPI journal, in appreciation of the work done.

Impact Factor: 3.3 (2024); 5-Year Impact Factor: 3.5 (2024)

Imprint Information Journal Flyer Open Access ISSN: 2311-5637

Latest Articles

22 pages, 1012 KB

Open AccessArticle

Gas Endeavour Device for the Real-Time in Vitro Measurement of Carbon Dioxide and Methane Emissions Associated with Sheep Diets with Prickly Pear By-Products

by Riccardo Gannuscio, Giuseppe Maniaci and Massimo Todaro

Fermentation 2025, 11(9), 543; https://doi.org/10.3390/fermentation11090543 - 18 Sep 2025

Prickly pear by-products contain dietary fibre and bioactive components like polyphenols and flavonols, which can reduce total gas and methane emissions. To this end, an in vitro trial was carried out in duplicate utilizing three diets containing hay, concentrate, and two prickly pear [...] Read more.

Prickly pear by-products contain dietary fibre and bioactive components like polyphenols and flavonols, which can reduce total gas and methane emissions. To this end, an in vitro trial was carried out in duplicate utilizing three diets containing hay, concentrate, and two prickly pear by-products obtained after grinding the fruit peel and pastazzo (pulp + peel + seeds), which were ensiled with the addition of 12% wheat bran (raw weight). Based on the ingredient intake recorded in the in vivo study for 12 lactating ewes fed the three diets, an in vitro rumen fermentation study with the innovative Gas Endeavour system (GES) was performed, and the Gage R&R statistical method was used to evaluate the accuracy of the total gas and methane production detected by the GES device. Fermented liquor samples for each diet were used to calculate the disappearance of organic matter and neutral detergent fibre. Shotgun metagenome sequencing analysis was used to evaluate the effect of diet on the rumen fluid microbiota, and it was found that the parameters of repeatability and reproducibility of the total gas and the methane produced after 24 h were satisfactory. Prickly pear by-products display high fermentability for the peel and low fermentability for pastazzo silage, which generates lower total gas and methane emissions. This diminished methane gas production is not correlated with the relative abundance of methanogens. The different chemical and nutritional composition of the three diets altered the rumen bacteria, albeit only slightly, with particular reference to the Succinivibrio and Selenomonas genera. In conclusion, prickly pear peel silage displayed acceptable fermentation traits, which could support its utilization in sheep diets. Full article

40 pages, 4383 KB

Open AccessArticle

Chitosan-Based Edible Films as Innovative Preservation Tools for Fermented and Dairy Products

by Fadime Seyrekoğlu and Esra Efdal

Fermentation 2025, 11(9), 542; https://doi.org/10.3390/fermentation11090542 - 18 Sep 2025

Extending the shelf life and ensuring microbial stability of processed foods are key objectives in the food industry. In this study, edible films containing chitosan, chitosan + thyme (Thymus vulgaris) oil, and chitosan + rosemary (Rosmarinus officinalis) oil were [...] Read more.

Extending the shelf life and ensuring microbial stability of processed foods are key objectives in the food industry. In this study, edible films containing chitosan, chitosan + thyme (Thymus vulgaris) oil, and chitosan + rosemary (Rosmarinus officinalis) oil were applied to traditional and industrial Cecil cheese using the dipping method, with control groups for each production type. Samples were stored at 4 ± 1 °C for 45 days, and physical (color, water activity, and texture), chemical (pH, acidity, and dry matter), microbiological (total aerobic mesophilic bacteria, yeast-mold, coliforms, and lactic acid bacteria), and sensory analyses were performed on days 1, 15, 30, and 45. Results indicated that chitosan-based films effectively limited microbial growth, with the chitosan + rosemary oil combination being particularly effective in reducing microbial load and maintaining textural stability. Traditional cheeses achieved higher overall acceptability, while purchase intent was greater for industrial products. Coated samples exhibited slower pH decline and more stable dry matter content; industrial cheeses retained moisture more effectively. Texture profile analysis showed more stable chewiness and springiness values in coated samples. In conclusion, natural edible films represent an effective approach for extending shelf life and preserving quality, particularly in traditional cheeses with fibrous structures and shorter shelf lives. Full article

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

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16 pages, 2215 KB

Open AccessArticle

Use of Lachancea thermotolerans and Metschnikowia pulcherrima to Improve Acidity and Sensory Profile of Verdejo Wines from Different Vine Management Systems

by María Soler, Juan Manuel Del Fresno, María Antonia Bañuelos, Antonio Morata and Iris Loira

Fermentation 2025, 11(9), 541; https://doi.org/10.3390/fermentation11090541 - 18 Sep 2025

A proper understanding of viticultural and oenological strategies is essential to adapt to climate change and consumer demands. The objective of this study was to evaluate the impact of different viticultural treatments and yeast strains on the chemical composition and sensory perception of [...] Read more.

A proper understanding of viticultural and oenological strategies is essential to adapt to climate change and consumer demands. The objective of this study was to evaluate the impact of different viticultural treatments and yeast strains on the chemical composition and sensory perception of wine. Two Verdejo musts, a control must (Must O) and one obtained with innovative viticultural strategies (Must E), were fermented with Saccharomyces cerevisiae, Lachancea thermotolerans, and a co-incubation of Lachancea thermotolerans with Metschnikowia pulcherrima. Fermentations with L. thermotolerans increased lactic acid content, reducing pH (a decrease of 0.2 points compared to controls) and having a positive impact on the perception of freshness. Wines fermented from Must E showed better colour parameters and a higher production of fermentative volatile compounds, but higher ethanol content and lower acidity. In contrast, wines fermented from Must O exhibited a more balanced aromatic profile, with fewer carbonyl compounds and higher alcohols (a 30% reduction in carbonyl compounds in wines fermented with non-Saccharomyces), which made them more harmonious in the sensory evaluations. The results highlight the importance of a good selection of viticultural and oenological strategies to achieve a desirable sensory profile under changing climatic conditions, highlighting the positive impact of non-Saccharomyces yeasts in improving acidity and aromatic profile. Full article

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

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15 pages, 1506 KB

Open AccessArticle

Productivity, Fermentation Parameters, and Chemical Composition of Silages from Biomass Sorghum Hybrids in Ratoon Crop

by Yara América da Silva, Marco Antonio Previdelli Orrico Junior, Marciana Retore, Gessí Ceccon, Isabele Paola de Oliveira Amaral, Ana Carolina Amorim Orrico, Giuliano Reis Pereira Muglia and Tatiane Fernandes

Fermentation 2025, 11(9), 540; https://doi.org/10.3390/fermentation11090540 - 18 Sep 2025

Biomass sorghum stands out for its high dry matter yield and ratooning ability, enabling additional harvests and silage production. This study evaluated the productive potential and fermentation quality of silages from ratoon biomass sorghum hybrids. A 5 × 2 factorial randomized block design [...] Read more.

Biomass sorghum stands out for its high dry matter yield and ratooning ability, enabling additional harvests and silage production. This study evaluated the productive potential and fermentation quality of silages from ratoon biomass sorghum hybrids. A 5 × 2 factorial randomized block design was used, with five hybrids (CMSXS5039, CMSXS5044, CMSXS7102, CMSXS7103, and BRS 716) grown in two municipalities of Mato Grosso do Sul, Brazil (Dourados and Jateí). Dry matter production (DMP) did not differ (p > 0.05) among the hybrids within each municipality; however, overall yield was higher in Jateí, averaging 12 t DM/ha. In Dourados, CMSXS5039 and CMSXS5044 showed the highest lactic acid concentrations (46.71 and 59.73 g/kg DM), whereas in Jateí, CMSXS7102, CMSXS7103, and BRS 716 stood out (45.70, 44.78, and 40.77 g/kg DM, respectively), among the sites, Jateí had the greater lactic acid production (49.95 g/kg DM). Aerobic stability (AS) averaged 28.5 h, with higher values in Dourados (p < 0.05), about 16 h longer than in Jateí. BRS 716 and CMSXS5044 presented the highest crude protein contents (115.17 and 118.33 g/kg DM). CMSXS5039 grown in Jateí had the lowest neutral detergent fiber and the highest starch and non-fiber carbohydrate values. Biomass sorghum hybrids exhibited good yield potential and good silage quality even under low rainfall conditions, with CMSXS5039 best suited for more energetic diets and BRS 716 and CMSXS5044 for more proteic diets. Full article

(This article belongs to the Special Issue Application of Fermentation Technology in Animal Nutrition: 2nd Edition)

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20 pages, 9451 KB

Open AccessArticle

Aeration Rate in Tertiary Treatment of Anaerobic Effluent from Soft Drink Industry by Co-Cultivation Between Penicillium gravinicasei and Microalgae

by João Victor Oliveira Nascimento da Silva, Carlos Eduardo de Farias Silva, Jânio Nunes Sampaio, Bruno Roberto dos Santos, Tácia Souza da Silva, Brígida Maria Villar da Gama, Anderson Correia da Silva, Albanise Enide da Silva and Renata Maria Rosas Garcia Almeida

Fermentation 2025, 11(9), 539; https://doi.org/10.3390/fermentation11090539 - 17 Sep 2025

The soft drink industry generates effluents with high organic loads and contaminants such as nitrogen and phosphorus, requiring sequential secondary and tertiary treatments to meet international discharge standards. Moving beyond traditional monocultures, this study developed a microbial consortium (forming microalga–fungus pellets), demonstrating a [...] Read more.

The soft drink industry generates effluents with high organic loads and contaminants such as nitrogen and phosphorus, requiring sequential secondary and tertiary treatments to meet international discharge standards. Moving beyond traditional monocultures, this study developed a microbial consortium (forming microalga–fungus pellets), demonstrating a synergistic combination due to the resistance of the pellets, enhancing the treatment efficiency, and facilitating the recovery of the microbial sludge produced. Specifically, the treatment of anaerobic effluents (tertiary treatment) from the soft drink industry using consortia of the fungus Penicillium gravinicasei and the microalgae Tetradesmus obliquus and Chlorella sp. in aerated reactors was evaluated, analyzing the impact of aeration rates (0.5–3.5 vvm) on pollutant removal and microbial sludge production. The results showed that moderate aeration rates (1.5 vvm) optimized the removal of COD (up to 92.5%), total nitrogen (TN) (up to 79.3%), and total phosphorus (TP) (up to 83.4%) in just 2.5 h. Furthermore, excessive aeration reduced treatment efficiency due to microbial stress and difficulty in forming microalga–fungus pellets. The Chlorella sp. consortium showed greater stability, while T. obliquus was more sensitive to the aeration rate. Microbial sludge production was also optimized at around 1.5 vvm, consequence of the pollutant removal, with the formation of pellets that facilitated biomass harvesting. Full article

(This article belongs to the Special Issue Cyanobacteria and Eukaryotic Microalgae (2nd Edition))

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40 pages, 1751 KB

Open AccessReview

Lactic Acid Bacteria-Derived Exopolysaccharides: Dual Roles as Functional Ingredients and Fermentation Agents in Food Applications

by Ricardo H. Hernández-Figueroa, Aurelio López-Malo and Emma Mani-López

Fermentation 2025, 11(9), 538; https://doi.org/10.3390/fermentation11090538 - 17 Sep 2025

Exopolysaccharides (EPSs) produced by lactic acid bacteria (LAB) have received special attention as valuable products due to their potential applications as techno-functional and bioactive ingredients in foods. EPS production and consumption are an age-old practice in humans, as evidenced by fermented foods. Over [...] Read more.

Exopolysaccharides (EPSs) produced by lactic acid bacteria (LAB) have received special attention as valuable products due to their potential applications as techno-functional and bioactive ingredients in foods. EPS production and consumption are an age-old practice in humans, as evidenced by fermented foods. Over the last two decades, extensive research has examined, analyzed, and reported a wide variety of EPSs from several LAB strains, as well as their techno-functional properties in foods. Also, research efforts focused on EPS characterization and yield production have been carried out. In food applications, EPS quantification and characterization in situ (direct fermentation) took place in various matrices (dairy, bread, plant-based fermented, and meat products). EPS direct application (ex situ) has been less investigated despite its better structural–functional control and use in non-fermented foods. Fewer EPS investigations have been conducted related to health benefits in humans and their mechanisms of action. The composition and functionality of EPSs vary depending on the LAB strain and food matrix used to produce them; thus, various challenges should be addressed before industrial applications are performed. This review aims to compile and summarize the recent findings on EPSs produced by LAB, highlighting their yield, culture production, techno-functional role in foods, food applications, and health benefits in clinical trials. It examines their dual applications, whether as purified functional ingredients (ex situ) or as fermentation products (in situ), and critically assesses both technological and bioactive implications. Also, it explores production challenges, regulatory considerations, and future perspectives for sustainable and tailored applications of EPSs in food innovation. Full article

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

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20 pages, 1645 KB

Open AccessReview

Smart and Functional Probiotic Microorganisms: Emerging Roles in Health-Oriented Fermentation

by Karina Teixeira Magalhães, Raquel Nunes Almeida da Silva, Adriana Silva Borges, Ana Elisa Barbosa Siqueira, Claudia Puerari and Juliana Aparecida Correia Bento

Fermentation 2025, 11(9), 537; https://doi.org/10.3390/fermentation11090537 - 16 Sep 2025

The incorporation of probiotic microorganisms into fermented foods has long been recognized as a promising strategy to enhance gut health and overall well-being. Conventional probiotics, mainly from the bacterial genera Lactobacillus, Bifidobacterium, Lacticaseibacillus, Levilactobacillus, Lactiplantibacillus and yeast genus Saccharomyces [...] Read more.

The incorporation of probiotic microorganisms into fermented foods has long been recognized as a promising strategy to enhance gut health and overall well-being. Conventional probiotics, mainly from the bacterial genera Lactobacillus, Bifidobacterium, Lacticaseibacillus, Levilactobacillus, Lactiplantibacillus and yeast genus Saccharomyces, contribute to gastrointestinal homeostasis, immune modulation, and metabolic balance. Building on these foundations, recent advances in synthetic biology, systems microbiology, and genetic engineering have enabled the development of smart probiotics: engineered or selectively enhanced strains capable of sensing environmental cues and producing targeted bioactive compounds, such as neurotransmitters and anti-inflammatory peptides. These next-generation microorganisms offer precision functionality in food matrices and hold promise for applications in gastrointestinal health, immune support, and gut–brain axis modulation. However, their deployment also raises critical questions regarding biosafety, regulatory approval, and consumer acceptance. This review provides a comprehensive overview of the mechanisms of action, biotechnological strategies, and health-oriented fermentation applications of smart and functional probiotics, emphasizing their role in the future of personalized and evidence-based functional foods. Full article

(This article belongs to the Special Issue Emerging Microbial Technologies in Fermentation: Innovations in Food, Environmental, and Health Bioprocesses)

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21 pages, 1108 KB

Open AccessArticle

Alternaria, Tenuazonic Acid and Spoilage Yeasts Associated with Bunch Rots of the Southern Oasis of Mendoza (Argentina) Winegrowing Region

by Luciana Paola Prendes, María Gabriela Merín, Fabio Alberto Zamora, Claire Courtel, Gustavo Alberto Vega, Susana Gisela Ferreyra, Ariel Ramón Fontana, María Laura Ramirez and Vilma Inés Morata

Fermentation 2025, 11(9), 536; https://doi.org/10.3390/fermentation11090536 - 15 Sep 2025

A study was carried out to identify the filamentous fungi and yeasts present in rotten wine grapes from two subzones of the Southern oasis of Mendoza winegrowing region, to assess the occurrence of tenuazonic acid (TA), a mycotoxin produced by the Alternaria genus, [...] Read more.

A study was carried out to identify the filamentous fungi and yeasts present in rotten wine grapes from two subzones of the Southern oasis of Mendoza winegrowing region, to assess the occurrence of tenuazonic acid (TA), a mycotoxin produced by the Alternaria genus, and to evaluate the wine spoilage potential of the associated yeasts in vitro and during microvinifications. The main fungal genera present were Alternaria (69.3%), followed by Aspergillus (16.8%), Penicillium (9.3%), and Cladosporium (4.6%), while the dominant yeast species Metschnikowia pulcherrima (23.1%), Aureobasidium pullulans (20.2%) and Hanseniaspora uvarum (13.0%) were followed by H. vineae (11.6%), Zygosaccharomyces bailii (10.4%), and H. guilliermondii (9.2%). Additionally, 94.1% of the rotten samples were contaminated with TA, with the highest level found in the Cabernet Sauvignon variety. No geographic association was found in the incidence of the different fungal genera or yeast species, nor in the occurrence of TA. Almost all of the tested yeasts produced H₂S, the majority of the Hanseniaspora strains produced acetic acid, and only one M. pulcherrima strain produced off-flavours in in vitro tests. Wines co-fermented with H. uvarum L144 and S. cerevisiae showed higher volatile acidity and lower fruity aroma and taste intensity. Therefore, processing bunch rot could pose a toxicological and microbiological risk to winemaking due to the high incidence of Alternaria and TA, as well as the potential of the associated yeasts to spoil wine. Full article

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

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15 pages, 705 KB

Open AccessArticle

Pre-Fermentative Addition of Sodium and Calcium Bentonites on Chardonnay Wine Changes Heat Stability, Fermentation Kinetics, Chemistry, and Volatile Composition

by Miguel A. Pedroza, Sydney Fritsch, Kevin Bargetto and L. Federico Casassa

Fermentation 2025, 11(9), 535; https://doi.org/10.3390/fermentation11090535 - 13 Sep 2025

Protein stabilization in white wines commonly involves bentonite fining, yet the influence of bentonite type, dosage, and pre-fermentative treatment on wine composition and fermentation remains underexplored. This study assessed the effects of pre-fermentative additions of sodium and calcium bentonites at three dosage levels [...] Read more.

Protein stabilization in white wines commonly involves bentonite fining, yet the influence of bentonite type, dosage, and pre-fermentative treatment on wine composition and fermentation remains underexplored. This study assessed the effects of pre-fermentative additions of sodium and calcium bentonites at three dosage levels (24, 48, and 72 g/hL) on the fermentation kinetics, protein (heat) stability, and chemical and aromatic composition of Chardonnay wines under commercial winemaking conditions. Sodium bentonite at 72 g/hL achieved near-complete protein stabilization (ΔNTU = 3), while all calcium bentonite treatments required significantly higher cumulative dosages (up to 216 g/hL). Pre-fermentative bentonite additions led to modest reductions in primary amino nitrogen (up to 13.2 mg/L), resulting in extended alcoholic fermentation durations by up to 33 h and variable delays in malolactic fermentation across treatments. Volatile ester analysis revealed limited sensory impact, with isoamyl acetate showing the greatest reduction (up to −2.8 odor activity value; −39%) at higher bentonite levels, whereas ethyl decanoate remained largely unaffected. Overall, the pre-fermentative addition of sodium bentonite at 72 g/hL provided an effective strategy to reduce the need for post-fermentation fining while preserving key chemical and aromatic attributes of Chardonnay wine. Full article

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

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18 pages, 2094 KB

Open AccessArticle

The Construction of Corynebacterium glutamicum for Producing γ-Aminobutyric Acid and Analysis of the Fermentation Process

by Qijie Deng, Ying Wen, Runmei Zhang and Jun Cai

Fermentation 2025, 11(9), 534; https://doi.org/10.3390/fermentation11090534 - 13 Sep 2025

In this study, we constructed a recombinant Corynebacterium glutamicum strain for γ-aminobutyric acid (GABA) biosynthesis via the heterologous expression of glutamate decarboxylase (GAD) derived from Lactiplantibacillus plantarum. We systematically analyzed the fermentation strategy, the balance between cell growth and GAD expression, and [...] Read more.

In this study, we constructed a recombinant Corynebacterium glutamicum strain for γ-aminobutyric acid (GABA) biosynthesis via the heterologous expression of glutamate decarboxylase (GAD) derived from Lactiplantibacillus plantarum. We systematically analyzed the fermentation strategy, the balance between cell growth and GAD expression, and the intracellular and extracellular glutamate and GABA levels during fermentation in recombinant C. glutamicum. The results demonstrated that a fermentation strategy combining variable-rate feeding with two-stage pH control at an initial glucose concentration of 50 g/L effectively enhanced cell proliferation, facilitated continuous glutamate synthesis and improved the catalytic efficiency of GAD. The intracellular and extracellular GABA synthesis improved up to 3.231 ± 0.024 g/L (a six-fold increase compared to the uncontrolled supplementation conditions). Furthermore, we fitted empirical equations relating cell growth, glucose consumption, GAD activity, and GABA synthesis during the fermentation. The maximum specific growth rate, glucose consumption rate, and GABA synthesis rate of recombinant C. glutamicum were 0.316 h⁻¹, 1.407 g/(g∙h), and 0.0697 g/L/h, respectively. The fermentation regulation strategy and the dynamic analysis of the fermentation process in this study provide support for future metabolic regulation strategies. Full article

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

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19 pages, 7933 KB

Open AccessArticle

Optimized Co-Fermentation of Seed Melon and Z. bungeanum Seed Meal with Saccharomyces cerevisiae L23: Valorization into Functional Feed with Enhanced Antioxidant Activity

by Liping Lu, Xue Zhang, Ziyi Yin, Rui Zhou, Yanli Zhu, Shanshan Liu and Dandan Gao

Fermentation 2025, 11(9), 533; https://doi.org/10.3390/fermentation11090533 - 12 Sep 2025

This study aimed to enhance the value of agricultural by-products by developing seed melon compound fermented feed (SMFF) using Saccharomyces cerevisiae L23. A two-stage optimization strategy was implemented. First, seed melon juice seed culture medium (SMCM) composition and fermentation conditions were optimized to [...] Read more.

This study aimed to enhance the value of agricultural by-products by developing seed melon compound fermented feed (SMFF) using Saccharomyces cerevisiae L23. A two-stage optimization strategy was implemented. First, seed melon juice seed culture medium (SMCM) composition and fermentation conditions were optimized to maximize S. cerevisiae L23 biomass through single-factor and response surface methodology (RSM) approaches. The SMCM medium was optimized to contain 0.06% MgSO₄·7H₂O, 0.2% KH₂PO₄, 0.65% (NH₄)₂SO₄, 0.1% pectinase, and 1.0% urea, and fermentation conditions with inoculation amount, fermentation time, fermentation temperature, and glucose addition were 6%, 28 h, 30 °C, and 0.5%, respectively. Furthermore, SMFF fermentation parameters were optimized via RSM, achieving S. cerevisiae L23 (10.35 lg CFU/g) and sensory evaluation score (83.1) at substrate ratio of 7:3 (seed melon juice: Zanthoxylum bungeanum seed meal), inoculation amount of 8%, and fermentation time of 36 h. Fermentation process significantly improved the nutritional profile of SMFF, increasing crude protein (13%) and vitamin C (VC) content (21%) while reducing neutral detergent fiber/acid detergent fiber (NDF/ADF) levels. SMFF also improved in vitro antioxidant capacity, with higher DPPH, ABTS, hydroxyl radical, and superoxide anion scavenging activities compared to SMFF control. This process efficiently valorized agricultural by-products into nutritionally enriched functional feed. Full article

(This article belongs to the Section Fermentation Process Design)

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20 pages, 4583 KB

Open AccessArticle

Seasonal Temperature Effects on EPS Composition and Sludge Settling Performance in Full-Scale Wastewater Treatment Plant: Mechanisms and Mitigation Strategies

by Fei Xie, Chenzhe Tian, Xiao Ma, Li Ji, Bowei Zhao, Muhammad Ehsan Danish, Feng Gao and Zhihong Yang

Fermentation 2025, 11(9), 532; https://doi.org/10.3390/fermentation11090532 - 12 Sep 2025

Seasonal temperature variations significantly impact biological wastewater treatment performance, particularly affecting extracellular polymeric substance (EPS) composition and sludge settling characteristics in activated sludge systems. This study investigated the temperature-induced EPS response mechanisms and their effects on nitrogen removal efficiency in a full-scale modified [...] Read more.

Seasonal temperature variations significantly impact biological wastewater treatment performance, particularly affecting extracellular polymeric substance (EPS) composition and sludge settling characteristics in activated sludge systems. This study investigated the temperature-induced EPS response mechanisms and their effects on nitrogen removal efficiency in a full-scale modified Bardenpho wastewater treatment plant, combined with laboratory-scale evaluation of EPS-optimizing microbial agents for performance enhancement. Nine-month seasonal monitoring revealed that when the wastewater temperature dropped below 15 °C, the total nitrogen (TN) removal efficiency decreased from 86.5% to 80.6%, with a trend of significantly increasing polysaccharides (PS) in dissolved organic matter (DOM) and loosely-bound EPS (LB-EPS) and markedly decreasing tightly-bound EPS (TB-EPS). During the low-temperature periods, when the sludge volume index (SVI) exceeded 150 mL/g, deteriorated settling performance could primarily be attributed to the reduced TB-EPS content and increased LB-EPS accumulation. Microbial community analysis showed that EPS secretion-promoting genera of Trichococcus, Terrimonas, and Defluviimonas increased during the temperature recovery phase rather than initial temperature decline phase. Laboratory-scale experiments demonstrated that EPS-optimizing microbial agents dominated by Mesorhizobium (54.2%) effectively reduced protein (PN) and PS contents in LB-EPS by 70.2% and 54.5%, respectively, while maintaining stable nutrient removal efficiency. These findings provide mechanistic insights into temperature–EPS interactions and offer practical technology for improving winter operation of biological wastewater treatment systems. Full article

(This article belongs to the Section Industrial Fermentation)

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20 pages, 1067 KB

Open AccessArticle

A Potential of Agro-Industrial Biowaste as Low-Cost Substrates for Carotenoid Production by Rhodotorula mucilaginosa

by Olja Šovljanski, Dragoljub Cvetković, Tara Budimac, Anja Vučetić, Ana Tomić, Teodora Marić and Aleksandra Ranitović

Fermentation 2025, 11(9), 531; https://doi.org/10.3390/fermentation11090531 - 12 Sep 2025

The sustainable production of natural pigments is gaining attention as industries seek alternatives to synthetic additives. This study explored agro-industrial biowastes as feedstocks for carotenoid biosynthesis by Rhodotorula mucilaginosa (natural isolate from Jerusalem artichoke), aiming to identify an optimal substrate that combines high [...] Read more.

The sustainable production of natural pigments is gaining attention as industries seek alternatives to synthetic additives. This study explored agro-industrial biowastes as feedstocks for carotenoid biosynthesis by Rhodotorula mucilaginosa (natural isolate from Jerusalem artichoke), aiming to identify an optimal substrate that combines high productivity with economic and environmental feasibility. Thirteen biowastes, including grape pomace, crude glycerol, chicken feathers, sugar beet juice, and pea protein isolate, were systematically evaluated for their impact on yeast growth and pigment accumulation. Carotenoid yields ranged from 21.4 to 187.2 mg/100 g dry weight, with the highest volumetric productivity achieved in pea protein isolate (14.98 mg/L), untreated white grape pomace (14.09 mg/L), and crude glycerol (13.87 mg/L). To assess scalability, a simplified techno-economic and sustainability analysis was applied, revealing that although pea protein isolate offered the best yields, its high market cost limited industrial feasibility. In contrast, untreated grape pomace and crude glycerol emerged as low-cost, abundant alternatives with strong circular bioeconomy potential. Fed-batch bioreactor validation using untreated grape pomace confirmed its suitability, achieving a 43% improvement in carotenoid productivity (20.1 mg/L) compared to shake-flask trials. These results position untreated grape pomace as the optimal substrate–strategy combination for sustainable carotenoid production linking agro-waste valorization with high-value bioproduct generation. This study provides both experimental evidence and economic rationale for integrating winery residues into industrial pigment production chains, advancing yeast biotechnology toward more circular and resource-efficient models. Full article

(This article belongs to the Special Issue Research on Yeast: Diversity, Biotechnology Potential, and Industrial Applications)

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18 pages, 10388 KB

Open AccessArticle

Effect of Inoculation of Lactic Acid Bacteria and Fibrolytic Enzymes on Microbiota in the Terminal and Aerobically Exposed Short-Growing Season Whole-Plant Corn Silage

by Chunli Li, Jayakrishnan Nair, Eric Chevaux, Tim A. McAllister and Yuxi Wang

Fermentation 2025, 11(9), 530; https://doi.org/10.3390/fermentation11090530 - 10 Sep 2025

An experiment was conducted to evaluate the effects of mixed lactic acid bacteria (LAB) plus fibrolytic enzymes (xylanase + β-glucanase) on bacterial and fungal communities in terminal and aerobically exposed whole-plant corn silage ensiled in a temperate zone. Short-season corn forage was either [...] Read more.

An experiment was conducted to evaluate the effects of mixed lactic acid bacteria (LAB) plus fibrolytic enzymes (xylanase + β-glucanase) on bacterial and fungal communities in terminal and aerobically exposed whole-plant corn silage ensiled in a temperate zone. Short-season corn forage was either uninoculated (C) or inoculated (I) with a mixture of LAB containing 1.5 × 10⁵ colony-forming units (cfu)/g Lentilactobacillus hilgardii, 1.5 × 10⁵ cfu/g of Lentilactobacillus buchneri, and 1.0 × 10⁵ cfu/g Pediococcus pentosaceus plus a combination of xylanase + β-glucanase. Silage samples were taken after ensiling in bag silos for 418 days (terminal silage; TS), with subsamples of TS subsequently exposed to air for 14 days (aerobically exposed silage; AS). Regardless of treatment, Firmicutes, Proteobacteria, Cyanobacteria, and Actinobacteria were the predominant phyla in the bacterial microbiome, whilst Ascomycota and Basidiomycota were the predominant phyla in the fungal microbiome in both TS and AS. Lactobacillus, Acetobacter, and Bacillus were the most abundant bacterial genera, whilst Candida, Aspergillus, Vishniacozyma, Pichia, and Issatchenkia were the most abundant fungal genera. Use of silage additive did not change bacterial or fungal alpha or beta diversity during ensiling or aerobic exposure, but decreased (p < 0.01) the relative abundance (RA) of Proteobacteria in both TS and AS, increased (p < 0.01) RA of Firmicutes in AS, but did not affect the RA of fungal phyla in either TS or AS. At the genus level, the additive significantly decreased (p < 0.01) RA of Acetobacter in both TS and AS. The silage additive used in this study significantly affected the composition of multiple microbial genera during ensiling and aerobic exposure by shifting bacterial communities towards enhanced aerobic stability. Full article

(This article belongs to the Special Issue The Use of Lactobacillus in Forage Storage and Processing, 2nd Edition)

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14 pages, 578 KB

Open AccessArticle

Application of Hops (Humulus lupulus L.) and β-Acid Extract to Improve Aerobic Stability and In Vitro Ruminal Fermentation of Maralfalfa Grass Silage

by Lianne Romero-Vilorio, Bexy González-Mora, Yamicela Castillo-Castillo, Francisco Castillo-Rangel, Einar Vargas-Bello-Perez, Joel Dominguez-Viveros, Monserrath Felix-Portillo, Robin C. Anderson, Michael E. Hume, Michael D. Flythe, Omar G. Nájera-Pedraza, Jaime Salinas-Chavira and Oscar Ruiz-Barrera

Fermentation 2025, 11(9), 529; https://doi.org/10.3390/fermentation11090529 - 10 Sep 2025

The potential of hops (Humulus lupulus L.) and β-acid extract were evaluated for improving the quality of maralfalfa grass (Cenchrus purpureus) silage (with added sorghum grain, sorghum straw, and urea) during aerobic exposure and their residual effects on in vitro [...] Read more.

The potential of hops (Humulus lupulus L.) and β-acid extract were evaluated for improving the quality of maralfalfa grass (Cenchrus purpureus) silage (with added sorghum grain, sorghum straw, and urea) during aerobic exposure and their residual effects on in vitro ruminal fermentation characteristics. Silage samples and ground hops pellets (Galena and Chinook varieties) as well as β-acid mixtures were incubated at 37 °C for 24 h and then maintained under aerobic exposure for 12 h. The sample pH, counts of filamentous fungi, yeasts, and total coliforms, and volatile fatty acid (VFA) concentrations were determined. Subsequently, in vitro ruminal fermentation was conducted to determine total gas production and concentrations of hydrogen, methane, carbon dioxide, and VFAs. The β-acid treatment controlled yeast populations, but an increase (p < 0.05) in pH values was observed for the Galena and Chinook treatments compared to the Control. However, pH did not differ significantly (p > 0.05) between the Control and the β-acid treatment. Butyric acid concentrations in the silage were lower (p < 0.05) compared to the Control, except in the silage treatment with Galena. In the in vitro ruminal fermentation, the β-acid treatment showed higher butyric acid levels than the Chinook and Galena, but these differences were not significant (p > 0.05). There were no differences (p > 0.05) in methane between the treatments. An increase (p < 0.05) in propionic acid concentration was observed in the in vitro ruminal fermentation with β-acids. It was concluded that β-acids could help reduce silage deterioration during the aerobic phase, reducing the butyric acid and yeast populations, and their residual effect could improve ruminal fermentation, increasing propionate and acetate concentrations. Full article

(This article belongs to the Special Issue Fermentation Technologies for the Production of High-Quality Feed: 2nd Edition)

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14 pages, 5867 KB

Open AccessReview

Fermentation of Organic Wastes for Feed Protein Production: Focus on Agricultural Residues and Industrial By-Products Tied to Agriculture

by Dan He and Can Cui

Fermentation 2025, 11(9), 528; https://doi.org/10.3390/fermentation11090528 - 10 Sep 2025

Global population growth and dietary transition have intensified demand for livestock and aquaculture products, thereby escalating demand for high-quality animal feed. Conventional protein sources, including soybean meal and fishmeal, face severe supply constraints driven by intense competition for arable land, worsening water scarcity, [...] Read more.

Global population growth and dietary transition have intensified demand for livestock and aquaculture products, thereby escalating demand for high-quality animal feed. Conventional protein sources, including soybean meal and fishmeal, face severe supply constraints driven by intense competition for arable land, worsening water scarcity, overexploitation of fishery resources, and rising production costs. These challenges are especially pronounced within agricultural systems. Evidence demonstrates that converting agriculturally derived organic wastes and agri-industrial by-products into feed protein can simultaneously alleviate these pressures, address agricultural waste disposal challenges, and reduce the carbon footprint associated with agricultural production. This review synthesizes fermentation processes for generating feed protein from agricultural organic wastes by employing functionally adapted microorganisms or microbial consortia. This distinguishes it from prior studies, which focused solely on single waste streams or individual microbial strains. It aims to advance feed protein production through an integrated approach that unites agricultural organic wastes, microorganisms, and fermentation processes, thereby promoting resource-oriented utilization of agricultural organic wastes and providing actionable solutions to alleviate feed protein scarcity. Full article

(This article belongs to the Special Issue Valorisation of Agro-Industrial By-Products Through Fermentation or Eco-Friendly Techniques)

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14 pages, 4497 KB

Open AccessArticle

Fungifuels: Polyethylene Decomposition and Electricity Generation with Aspergillus ochraceopetaliformis in Microbial Fuel Cell Systems

by Rojas-Flores Segundo, Magaly De La Cruz-Noriega, Nancy Soto-Deza, Nélida Milly Otiniano, Cabanillas-Chirinos Luis and Anibal Alviz-Meza

Fermentation 2025, 11(9), 527; https://doi.org/10.3390/fermentation11090527 - 9 Sep 2025

Plastic pollution is an increasingly pressing environmental concern due to its persistence in ecosystems. To address this issue, this study evaluates polyethylene biodegradation and bioelectricity generation using Aspergillus ochraceopetaliformis in microbial fuel cells (MFCs). Single-chamber MFCs were designed (three) with carbon and zinc [...] Read more.

Plastic pollution is an increasingly pressing environmental concern due to its persistence in ecosystems. To address this issue, this study evaluates polyethylene biodegradation and bioelectricity generation using Aspergillus ochraceopetaliformis in microbial fuel cells (MFCs). Single-chamber MFCs were designed (three) with carbon and zinc electrodes, where the fungus was cultivated in a nutrient-rich medium to enhance its metabolic activity. Parameters such as pH, power density, and FTIR spectra were monitored to assess plastic biodegradation. The results demonstrated a significant reduction in polyethylene mass and structure, along with a maximum generation of 0.921 V and 4.441 mA on day 26, with a power density of 0.148 mW/cm² and a current of 5.847 mA/cm². The optimal pH for fungal activity in the MFC was recorded at 7.059. Furthermore, FTIR analysis revealed a decrease in peak intensity at 1470 cm⁻¹ and 723 cm⁻¹, indicating structural modifications in the treated plastics. Furthermore, microbial fuel cells connected in series successfully powered an LED bulb, generating a maximum voltage of 2.78 V. These findings confirm the feasibility of using Aspergillus ochraceopetaliformis for biodegradation and bioelectricity generation, although practical applications require further optimization of system conditions and improvements in long-term stability. This research contributes to the development of biotechnological strategies for plastic waste management, sustainable integrating approaches with energy potential. Full article

(This article belongs to the Section Industrial Fermentation)

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20 pages, 6133 KB

Open AccessArticle

PerR Deletion Enhances Oxygen Tolerance and Butanol/Acetone Production in a Solvent-Degenerated Clostridium beijerinckii Strain DS

by Chuan Xiao, Jianxiong Dou, Naan Zhang, Laizhuang Liu, Shengjie Du, Xiancai Rao and Longjiang Yu

Fermentation 2025, 11(9), 526; https://doi.org/10.3390/fermentation11090526 - 8 Sep 2025

The industrial potential of Clostridium beijerinckii for acetone–butanol–ethanol (ABE) fermentation is limited by oxygen sensitivity and suboptimal solvent productivity. Peroxide repressor (PerR), a key negative regulator protein, is reported to suppress the oxidative stress defense system in anaerobic clostridia, leading to poor survival [...] Read more.

The industrial potential of Clostridium beijerinckii for acetone–butanol–ethanol (ABE) fermentation is limited by oxygen sensitivity and suboptimal solvent productivity. Peroxide repressor (PerR), a key negative regulator protein, is reported to suppress the oxidative stress defense system in anaerobic clostridia, leading to poor survival of bacteria under aerobic conditions. However, the regulatory mechanism underlying this phenomenon remains unclear. This study demonstrates that targeted deletion of perR (Cbei_1336) in the solvent-deficient strain C. beijerinckii DS confers robust oxygen tolerance and enhances ABE fermentation performance. The engineered perR mutant exhibited unprecedented aerobic growth under atmospheric oxygen (21% O₂), achieving a (3.79 ± 0.09)-fold increase in biomass accumulation, a (2.84 ± 0.12)-fold improvement in glucose utilization efficiency, a (57.23 ± 0.01)-fold elevation in butanol production, and a (32.78 ± 0.02)-fold amplification in acetone output compared to the parental strain. Transcriptomic analysis revealed that perR knockout simultaneously upregulated oxidative defense systems and activated ABE pathway-related genes. This genetic rewiring redirected carbon flux from acidogenesis to solventogenesis, yielding a (9.64 ± 0.90)-fold increase in total solvent titer (15.61 ± 0.89 vs. 1.62 ± 0.12 g/L) and a (2.71 ± 0.04)-fold rise in volumetric productivity (0.19 ± 0.01 vs. 0.07 ± 0.01 g/L/h). Our findings establish PerR as a master regulator of both oxygen resilience and metabolic reprogramming, providing a scalable engineering strategy for industrial oxygen-tolerant ABE bioprocessing toward low-cost biobutanol production. Full article

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

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14 pages, 3172 KB

Open AccessArticle

Transforming Tilapia into Indoleacetic Acid-Containing Biostimulants: Synergistic Effect of Enzymolysis and Multi-Strain Fermentation

by Hanyi Xie, Bin Zhong, Qimin Zhang, Xi Hu, Xuesen Xia, Hong Xie and Zhenqiang Wu

Fermentation 2025, 11(9), 525; https://doi.org/10.3390/fermentation11090525 - 8 Sep 2025

Following new trends in green development, many studies have focused on the high-value utilization of fish resources through green biological processes. This study innovatively introduced a one-step process of mixed strain–enzyme synergy (MES) with which to prepare tilapia hydrolysates and explored the synergistic [...] Read more.

Following new trends in green development, many studies have focused on the high-value utilization of fish resources through green biological processes. This study innovatively introduced a one-step process of mixed strain–enzyme synergy (MES) with which to prepare tilapia hydrolysates and explored the synergistic effects of strains and enzymes on both the protein hydrolysis process and its products’ characteristics via comparative experiments. Further, soybean was used as a model crop to verify the agronomic effects of the hydrolysates. The addition of exogenous papain increased hydrolysis by 31.94% compared to the fermentation-only group. Peptides and amino acids contents in the mixed strains were higher than those in the single fermentation process (p < 0.05), while 8.46 mg/L of indoleacetic acid was produced through fermentation. Hydrolysates promoted the growth of lateral roots in soybean seedlings (p < 0.05) via the use of a 2500-fold dilution of the biostimulant, increasing the root area and stem length and reducing the sugar content of soybean seedlings by 1.59-, 1.44- and 1.69-fold compared to those in Hoagland’s nutrient solution. These results lay a foundation for the biological preparation of biostimulants for hydroponic vegetables through the utilization of fish waste resources, aligning with green development goals. Full article

(This article belongs to the Special Issue Fermentation of Organic Waste for High-Value-Added Product Production—2nd Edition)

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16 pages, 2374 KB

Open AccessArticle

Production of Nutritional Protein Hydrolysates by Fermentation of Black Soldier Fly Larvae

by Penghui Zhang, Kelyn Seow, Leo Wein, Rachel Steven, Rebecca J. Case, Yulan Wang and Patricia L. Conway

Fermentation 2025, 11(9), 524; https://doi.org/10.3390/fermentation11090524 - 8 Sep 2025

The black soldier fly (Hermetia illucens) has become one of the most promising alternative protein sources in the feed and food industry. The aim of this work was to utilize microbial fermentation to enhance the nutritional properties of black soldier fly [...] Read more.

The black soldier fly (Hermetia illucens) has become one of the most promising alternative protein sources in the feed and food industry. The aim of this work was to utilize microbial fermentation to enhance the nutritional properties of black soldier fly larvae (BSFL) as a food ingredient for human consumption by optimizing the amino acid profile and small peptide content. Free amino acids (FAA) have a critical role in human nutrition and bioavailability. Unlike whole proteins that require enzymatic breakdown in the digestive tract, FAA are directly absorbable by the small intestine, allowing for rapid utilization in protein synthesis and metabolic functions. BSFL pastes were fermented using Lacticaseibacillus paracasei (PCB 030) or a mixed starter culture preparation, and results were compared to pea protein and BSFL pastes that were enzymatically hydrolyzed. The resultant hydrolyzed BSFL pastes were analyzed for free amino acids and small peptides. The L. paracasei PCB 030 fermented BSFL pastes yielded significantly higher amounts of free amino acids than the control or pastes fermented using a commercial starter culture (named F-LC). The increased FAA availability in fermented BSFL makes it a more efficient protein source for human consumption. The L. paracasei PCB 030 fermented pastes showed an increase in small peptides after three days fermentation; nearly 80% of normalized abundances of small peptides increased by over 100 times compared to day zero (before the fermentation started). Over 90% of these small peptides consisted of more than 50% hydrophobic amino acids, which may contribute to their antioxidant and antibacterial properties. This study provides a promising and industrially practical process for hydrolyzing BSFL protein to yield a functional protein hydrolysate with an enhanced nutritional profile. Full article

(This article belongs to the Special Issue 10th Anniversary of Fermentation: Feature Papers in the "Fermentation for Food and Beverages" Section)

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