Fermentation

21 pages, 1583 KB

Open AccessArticle

Enhanced Biohydrogen Production Through Continuous Fermentation of Thermotoga neapolitana: Addressing By-Product Inhibition and Cell Viability in Different Bioreactor Modes

by Fabian Moll, Leon Hansen, Julian Tix and Nils Tippkötter

Fermentation 2025, 11(10), 579; https://doi.org/10.3390/fermentation11100579 - 9 Oct 2025

Abstract

This study investigates the efficient biogenic production of hydrogen via the thermophilic bacterium Thermotoga neapolitana, focusing on optimising process configurations to maximise yield and productivity. To determine optimal conditions, a 1 L anaerobic bioreactor with online gas analytics was designed and tested [...] Read more.

This study investigates the efficient biogenic production of hydrogen via the thermophilic bacterium Thermotoga neapolitana, focusing on optimising process configurations to maximise yield and productivity. To determine optimal conditions, a 1 L anaerobic bioreactor with online gas analytics was designed and tested for batch, fed-batch and continuous fermentation. A maximum hydrogen production rate of 96.1 ± 1.7 Nml·L⁻¹·h⁻¹ was observed in the continuous reactor. The optimal dilution rate was 0.07 h⁻¹. Each dilution rate was kept for ≥56 h fermentation time and resulted in yields of 2.7–3.0 mol_H2·mol_glucose⁻¹. A consistently high cell viability (97%) was also observed across various dilution rates. A detailed carbon balance indicates acetate as the main by-product, closely linked to the hydrogen production pathway. Compared to fed batch and batch, the hydrogen production rate could be increased and remain constant over a longer time. In this way the continuous reactor design showed an additional method to produce hydrogen to the established ones. Fermentative hydrogen production is particularly promising when using carbohydrate containing biomass and biowaste, as it can be considered carbon dioxide neutral. Full article

(This article belongs to the Special Issue Fermentative Biohydrogen Production, 2nd Edition)

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13 pages, 2376 KB

Open AccessArticle

Enhancing Xylanase and Cellulase Production by Two Locally Isolated Fungal Strains Under Solid-State Fermentation of Water Hyacinth and Sugarcane Bagasse

by Carlos Soltero-Sánchez, Evelyn Romero-Borbón, Nestor David Ortega-de la Rosa, María Angeles Camacho-Ruiz and Jesús Córdova

Fermentation 2025, 11(10), 578; https://doi.org/10.3390/fermentation11100578 - 9 Oct 2025

Abstract

This study aimed to isolate and identify fungi capable of producing xylanases and cellulases. Thirty-eight fungal strains were isolated from decaying water hyacinth (WH), and two were selected based on their superior enzyme production under solid-state fermentation (SSF). The strains were identified through [...] Read more.

This study aimed to isolate and identify fungi capable of producing xylanases and cellulases. Thirty-eight fungal strains were isolated from decaying water hyacinth (WH), and two were selected based on their superior enzyme production under solid-state fermentation (SSF). The strains were identified through morphological, cultural, and molecular analyses as Aspergillus austwickii B6 and Trichoderma harzianum M7. Their ribosomal ITS sequences were deposited in GenBank under accession numbers PQ142799.1 for A. austwickii B6 and PQ007458.1 for T. harzianum M7. Enzyme production was evaluated under SSF using eight culture medium variants prepared with natural or pretreated biomasses of WH and sugarcane bagasse (SCB), combined with either NaNO₃ or (NH₄)₂SO₄ as nitrogen sources. The maximum xylanase and cellulase activities were 752 and 65 U/g dry matter (DM), respectively, for A. austwickii B6, and 1724 and 152 U/g DM for T. harzianum M7, when cultivated on a low-cost medium composed of pretreated WH, (NH₄)₂SO₄, and a simple mineral salt solution. These findings highlight the potential of locally isolated fungal strains and lignocellulosic residues as cost-effective substrates and inducers of xylanase and cellulase production under SSF and underscore the importance of WH pretreatment to enhance substrate availability and maximize enzyme yields. Full article

(This article belongs to the Special Issue Lignocellulosic Biomass Valorisation, 2nd Edition)

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20 pages, 3391 KB

Open AccessArticle

The Effects of Pre-Fermentative Treatments on the Aroma of Krstač and Žižak Wines

by Valerija Madžgalj, Iris Đorđević, Ivana Sofrenić and Aleksandar Petrović

Fermentation 2025, 11(10), 577; https://doi.org/10.3390/fermentation11100577 - 7 Oct 2025

Abstract

Pre-fermentative treatments are essential in winemaking, as they significantly influence the quality and stability of white wines in particular. The synthesis of many compounds obtained from yeast, such as higher alcohols and esters, is influenced by the type and concentration of aromatic precursors [...] Read more.

Pre-fermentative treatments are essential in winemaking, as they significantly influence the quality and stability of white wines in particular. The synthesis of many compounds obtained from yeast, such as higher alcohols and esters, is influenced by the type and concentration of aromatic precursors present in the must, especially amino acids. Clarification has a positive effect on wine quality, mainly by improving organoleptic properties, with flavour being the most affected. In this study, the influences of different static settling times, different pressures during must extraction and the addition of different bentonite concentrations to the must on the aroma of wines from the autochthonous grape varieties Krstač and Žižak were investigated. The identification of aromatic compounds in the wine was performed using GC/FID-MS analysis. Wine subjected to the longest static settling time (30 h) showed the highest concentration of esters. Krstač wine, which underwent a 30 h of settling, was characterised by an increased concentration of esters, such as isoamyl acetate, ethyl decanoate and ethyl hexanoate, while Žižak wine was characterised by the presence of 2-phenylethyl acetate and isoamyl acetate. The total fatty acid content in Krstač wine obtained by pressing was higher (14.90 mg/L) than in wine produced from free-run juice (8.04 mg/L). Full article

(This article belongs to the Special Issue Wine and Beer Fermentation, 2nd Edition)

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18 pages, 6472 KB

Open AccessArticle

High-Mountain Tuber Products Improve Selectively the Development and Detoxifying Capacity of Lactobacilli Strains as an Innovative Culture Strategy

by Cecilia Hebe Orphèe, María Inés Mercado, Fernando Eloy Argañaraz Martínez, Mario Eduardo Arena and Elena Cartagena

Fermentation 2025, 11(10), 576; https://doi.org/10.3390/fermentation11100576 - 6 Oct 2025

Abstract

The study provides valuable insights into the sustainable utilization of edible tuber peels from the high mountains of the Argentinian Puna, which constitutes promising reserves of bioactive phenolic compounds with the potential to enhance the biofunctional properties of lactic acid bacteria. Thirty-two extracts [...] Read more.

The study provides valuable insights into the sustainable utilization of edible tuber peels from the high mountains of the Argentinian Puna, which constitutes promising reserves of bioactive phenolic compounds with the potential to enhance the biofunctional properties of lactic acid bacteria. Thirty-two extracts derived from peels of different varieties of tubers, such as Oxalis tuberosa Mol., Ullucus tuberosus Caldas, and Solanum tuberosum L. were incorporated into lactobacilli cultures and individually evaluated. These selectively enhance the development of the probiotic strain Lactiplantibacillus plantarum ATCC 10241 and of Lacticaseibacillus paracasei CO1-LVP105 from ovine origin, without promoting the growth of a pathogenic bacteria set (Escherichia coli O157:H12 and ATCC 35218, Salmonella enterica serovar Typhimurium ATCC 14028, and S. corvalis SF2 and S. cerro SF16), in small amounts. To determine the main phenolic group concentrated in the phytoextracts, a bio-guided study was conducted. The most significant results were obtained by O. tuberosa phytochemicals added to the culture medium at 50 µg/mL, yielding promising increases in biofilm formation (78% for Lp. plantarum and 43% for L. paracasei) and biosurfactant activity (112% for CO1-LVP105 strain). These adaptive strategies developed by bacteria possess key biotechnological significance. Furthermore, the bio-detoxification capacity of phenol and o-phenyl phenol, particularly of the novel strain CO1-LVP105, along with its mode of action and genetic identification, is described for the first time to our knowledge. In conclusion, lactobacilli strains have potential as fermentation starters and natural products, recovered from O. tuberosa peels, and added into culture media contribute to multiple bacterial biotechnological applications in both health and the environment. Full article

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20 pages, 3013 KB

Open AccessArticle

Exploring Static Biological Aging as a Method for Producing Low-Alcohol ‘Fino’ Type White Wines

by Raquel Muñoz-Castells, Lourdes Vega-Espinar, Juan Carlos García-García, Maria Trinidad Alcalá-Jiménez, Jaime Moreno-García, Cristina Lasanta and Juan Moreno

Fermentation 2025, 11(10), 575; https://doi.org/10.3390/fermentation11100575 - 5 Oct 2025

Abstract

Spanish “Fino”-style white wines are traditionally aged by a dynamic process under a flor veil of Saccharomyces cerevisiae, requiring ≥15% (v/v) ethanol, which is typically achieved through fortification. Market demand for lower-alcohol wines and the need to reduce [...] Read more.

Spanish “Fino”-style white wines are traditionally aged by a dynamic process under a flor veil of Saccharomyces cerevisiae, requiring ≥15% (v/v) ethanol, which is typically achieved through fortification. Market demand for lower-alcohol wines and the need to reduce production costs have encouraged the development of alternative approaches. Here, static biological aging was evaluated as a method for producing Fino-type wines with reduced ethanol content. Base wines with ~14% and ~15% (v/v) ethanol were aged for nine months, during which chemical, microbiological, and sensory parameters were analyzed, along with flor veil activity. Lower-ethanol wines showed greater flor activity, with approximately 20 more yeast isolates in the wines with 14% (v/v) ethanol. Higher acetaldehyde levels were detected in these wines, reaching about 377 mg L⁻¹ compared to 230 mg L⁻¹ in the control wines (≥15% v/v ethanol). Significant changes were observed in pH (3.13–3.47 vs. 3.04–3.46), volatile acidity (0.20–0.26 g L⁻¹ vs. 0.31–0.66 g L⁻¹), and several volatile compounds, resulting in chemical and sensory profiles consistent with traditional biologically aged wine. Static biological aging can yield lower-alcohol Fino-style white wines with sensory and chemical attributes comparable to the traditional fortified versions, providing a cost-effective alternative that aligns with evolving consumer preferences. Full article

(This article belongs to the Special Issue Scale-Up Challenges in Microbial Fermentation)

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43 pages, 1439 KB

Open AccessReview

Advances in Algae-Based Bioplastics: From Strain Engineering and Fermentation to Commercialization and Sustainability

by Nilay Kumar Sarker and Prasad Kaparaju

Fermentation 2025, 11(10), 574; https://doi.org/10.3390/fermentation11100574 - 4 Oct 2025

Abstract

The development of algal bioplastics offers a promising pathway toward sustainable materials that can mitigate reliance on fossil fuel-derived plastics. This article reviews recent advances in algal cultivation, strain optimization, biopolymer extraction, and processing technologies, alongside techno-economic and life cycle assessments. Special emphasis [...] Read more.

The development of algal bioplastics offers a promising pathway toward sustainable materials that can mitigate reliance on fossil fuel-derived plastics. This article reviews recent advances in algal cultivation, strain optimization, biopolymer extraction, and processing technologies, alongside techno-economic and life cycle assessments. Special emphasis is placed on integrated biorefinery models, innovative processing techniques, and the role of government–industry–academia partnerships in accelerating commercialization. The analysis incorporates both demonstrated algal systems and theoretical applications derived from established microbial processes, reflecting the emerging nature of this field. The environmental advantages, market readiness, and scalability challenges of algal bioplastics are critically evaluated, with reference to peer-reviewed studies and industrial pilot projects. The analysis underscores that while technical feasibility has been demonstrated, economic viability and large-scale adoption depend on optimizing yield, reducing production costs, and fostering collaborative frameworks. Future research priorities include enhancing strain performance via AI-enabled screening, expanding product valorization streams, and aligning regulatory standards to support global market integration. Full article

(This article belongs to the Special Issue Algae Biotechnology for Biofuel Production and Bioremediation)

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25 pages, 12805 KB

Open AccessReview

Bioremediation of Polycyclic Aromatic Hydrocarbons (PAHs) in Aqueous Environments: A Review of Biofiltration, Biosorption, and Biodegradation Strategies Using Living Fungal Mycelium

by Claudia Colmo, Martin Tegelaar and Phil Ayres

Fermentation 2025, 11(10), 573; https://doi.org/10.3390/fermentation11100573 - 2 Oct 2025

Abstract

Accelerating urbanisation and industrial activity have led to the widespread release of polycyclic aromatic hydrocarbons (PAHs), a class of persistent organic pollutants with serious ecological and health consequences. While physical and chemical remediation techniques are widely used, they often require nonrenewable resources and [...] Read more.

Accelerating urbanisation and industrial activity have led to the widespread release of polycyclic aromatic hydrocarbons (PAHs), a class of persistent organic pollutants with serious ecological and health consequences. While physical and chemical remediation techniques are widely used, they often require nonrenewable resources and generate secondary waste. Fungal-based bioremediation offers a promising alternative, leveraging the unique metabolic pathways and structural properties of fungi to break down or adsorb PAHs. This review focuses on three strategies of PAH remediation in aquatic environments: biofiltration, biosorption, and metabolic degradation. We conduct a comparison between conventional systems and fungal approaches with reference to the literature (2000–2025). Fungal matrices are identified as being able to capture and adsorb PAHs, facilitating localised remediation that capitalises on the biological capabilities of fungal organisms while requiring lower resource inputs than conventional methods. This review highlights fungal matrices as multifunctional water filtration membranes and provides insights for the application and development of engineered living materials (ELMs) for the water detoxification of PAHs. Full article

(This article belongs to the Special Issue Application of Fungi in Bioconversions and Mycoremediation)

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18 pages, 1770 KB

Open AccessArticle

Adapted Kefir Grains in Aqueous Extract of Licuri (Syagrus coronata): Development and Characterization of a Novel Non-Dairy Probiotic Beverage

by Elis dos Reis Requião, Janaina de Carvalho Alves, Suelen Neris Almeida Viana, Isadora Santana Araújo da Silva, Jéssica Maria Rio Branco dos Santos Ferro, Mariana Ferreira de Brito, Carolina Oliveira de Souza, Joselene Conceição Nunes Nascimento and Mariana Nougalli Roselino

Fermentation 2025, 11(10), 572; https://doi.org/10.3390/fermentation11100572 - 2 Oct 2025

Abstract

Fermented beverages have been highlighted for their beneficial effects on health, especially due to the presence of probiotic microorganisms. This study aimed to develop and characterize a beverage fermented from the aqueous extract of licuri (Syagrus coronata) with grains of milk [...] Read more.

Fermented beverages have been highlighted for their beneficial effects on health, especially due to the presence of probiotic microorganisms. This study aimed to develop and characterize a beverage fermented from the aqueous extract of licuri (Syagrus coronata) with grains of milk kefir and water kefir. Physical–chemical properties, microbial viability, storage stability, and in vitro resistance to the gastrointestinal tract (GIT), as well as microbiological safety and identification of isolated bacteria, were evaluated. The grains were fermented in licuri for 24 and 48 h, and the samples were compared with their respective controls. The analyses revealed that the licuri drink favored the growth of kefir grains, maintaining adequate microbial viability (>7 log CFU mL⁻¹ for lactic acid bacteria and >4 log CFU mL⁻¹ for yeasts), with good resistance to GIT (>60%) and physical–chemical properties for 20 days. The bacterial isolate was identified as Lacticaseibacillus paracasei, with a satisfactory safety profile. Licuri extract is therefore a promising matrix for the development of non-dairy functional beverages with potential probiotic properties. Full article

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

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16 pages, 2575 KB

Open AccessArticle

Release and Purification of Poly(3-hydroxybutyrate) P(3HB) via the Combined Use of an Autolytic Strain of Azotobacter vinelandii OP-PhbP3⁺ and Non-Halogenated Solvents

by Joshua Valencia, Daniel Segura, Claudia Aguirre-Zapata, Enrique Galindo and Carlos Peña

Fermentation 2025, 11(10), 571; https://doi.org/10.3390/fermentation11100571 - 2 Oct 2025

Abstract

P(3HB) is a biodegradable and biocompatible polymer, which can replace petroleum-derived plastics. Previous studies have shown that Azotobacter vinelandii strain OP-PhbP3⁺, which overexpresses the phasin protein PhbP3, produces high concentrations of P(3HB) and undergoes early autolysis, facilitating polymer release. The aim [...] Read more.

P(3HB) is a biodegradable and biocompatible polymer, which can replace petroleum-derived plastics. Previous studies have shown that Azotobacter vinelandii strain OP-PhbP3⁺, which overexpresses the phasin protein PhbP3, produces high concentrations of P(3HB) and undergoes early autolysis, facilitating polymer release. The aim of the present study was to evaluate the performance of this strain for P(3HB) production in 3 L bioreactors and assess the feasibility of a simplified recovery process. After 36 h of cultivation, rapid cell lysis was observed, resulting in a ~50% decrease in the protein content of the cell dry weight, without reducing P(3HB) concentration, which reached 4.6 g L⁻¹. Flow cytometry analysis revealed significant morphological changes during cultivation, which was consistent with the strain’s lytic behavior. The biomass recovered at 36 h was washed with SDS, obtaining a yield of 92.5% (respect to P(3HB) initial) and a purity of 97.6%. An alternative extraction procedure using the non-halogenated solvent cyclohexanone (CYC) resulted in an even higher yield of 97.8% with a purity of 99.3% of P(3HB). Notably, the weight average molecular weight of the polymer remained stable at 8000 kDa during the entire process. Overall, the combination of PhbP3 over-expression and environmentally friendly solvents, such as CYC, enabled efficient P(3HB) production with high yield and purity while preserving polymer quality. Full article

(This article belongs to the Section Fermentation Process Design)

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20 pages, 1130 KB

Open AccessArticle

The Effect of Modification of Wine Maceration Processes with the Addition of Ascorbic Acid and Yeast Culture on Biogenic Amine, Chemical, Microbial and Sensory Variables of Welschriesling Wine

by Lucia Šuľáková, Boris Semjon, Ivana Regecová, Peter Očenáš, Martin Bartkovský, Zuzana Megyesy Eftimová and Slavomír Marcinčák

Fermentation 2025, 11(10), 570; https://doi.org/10.3390/fermentation11100570 - 1 Oct 2025

Abstract

The aim of this work was to study the effects of modification of the skin maceration process by adding ascorbic acid and a yeast culture of Saccharomyces cerevisiae on the quality and safety of Welschriesling wine. The pH, total acids, SO₂, [...] Read more.

The aim of this work was to study the effects of modification of the skin maceration process by adding ascorbic acid and a yeast culture of Saccharomyces cerevisiae on the quality and safety of Welschriesling wine. The pH, total acids, SO₂, and alcohol content were significantly affected by the modification of the maceration (p < 0.001), except for the alcohol variable, which was not influenced by the skin maceration modifications of the measured values (p > 0.05). The antioxidant activity, total polyphenols, flavonoids, and ascorbic acid levels changed significantly during the experiment, including the maceration and maturation periods (p < 0.001). The observed histamine concentrations were below the recommended limit of 10 mg·L⁻¹ in each analysed sample. Histamine (HIS) and tyramine (TYR) amounts were significantly affected by the experimental factors (p < 0.001). After nine months of maturation, wine samples with ascorbic acid had 2.23 ± 0.00 and 0.35 ± 0.00 mg·L⁻¹ HIS and TYR content, respectively. On the other side, macerated wines without ascorbic acid had 3.05 ± 0.10 and 0.37 ± 0.05 mg·L⁻¹ HIS and TYR content, respectively. Modified vinification procedure with ascorbic acid negatively affected wine samples in the overall sensory evaluation scores of the wines (p < 0.001). Full article

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

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14 pages, 606 KB

Open AccessArticle

Comparison of Gelatin and Plant Proteins in the Clarification of Grape Musts Using Flotation Techniques

by Áron Pál Szövényi, Annamária Sólyom-Leskó, Balázs Nagy, Zsuzsanna Varga, Noémi Aletta Németh and Diána Ágnes Nyitrainé Sárdy

Fermentation 2025, 11(10), 569; https://doi.org/10.3390/fermentation11100569 - 1 Oct 2025

Abstract

The study compared the effects of conventional and vegan processing aids in the clarification of must, focusing on the phenolic and sensory characteristics of must and wine. The hypothesis was that plant protein could provide results similar to those of conventional aids containing [...] Read more.

The study compared the effects of conventional and vegan processing aids in the clarification of must, focusing on the phenolic and sensory characteristics of must and wine. The hypothesis was that plant protein could provide results similar to those of conventional aids containing proteins of animal origin, especially in aromatic grapes, where hyperoxidation is avoided. Conducted in 2024 in Etyek-Buda, Hungary, the initial trials subjected the Irsai Olivér grape must to gravity sedimentation with various agents. Vegan processing aids, notably the combination of pea protein and chitin-glucan, showed a gentle impact on the assimilable nitrogen content and a similar reduction in turbidity to those with animal proteins. Nitrogen flotation trials compared gelatin and the vegan alternative (a combination of pea protein and chitin–glucan) in Irsai Olivér and Chardonnay must clarification. The removal of phenolic substances was monitored using the Folin–Ciocalteu method, the acid butanol assay, and the vanillin assay. In addition, nitrogen levels were evaluated before and after the flotation experiments. The plant-based processing aid effectively improved the sensory quality of Irsai Olivér. However, the gelatin-treated Chardonnay was fresher and less bitter than the vegan option, which was less balanced and more bitter with weaker aroma and flavor. Full article

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

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29 pages, 5748 KB

Open AccessArticle

Metatranscriptome Analysis of Sheep Rumen Reveals Methane Production Changes Induced by Moringa oleifera as a Dietary Supplement

by Alicia Alejandra Grijalva-Hinojos, Vicente Arnau, Wladimiro Díaz, Samuel Piquer, Daniel Díaz-Plascencia, Yamicela Castillo-Castillo, Joel Domínguez-Viveros and Perla Lucia Ordoñez-Baquera

Fermentation 2025, 11(10), 568; https://doi.org/10.3390/fermentation11100568 - 1 Oct 2025

Abstract

Global warming has become a significant public health concern, with intensive livestock farming as a major contributor. To mitigate greenhouse gas emissions, strategies such as manipulating the ruminal environment with dietary additives are essential. This study evaluated Moringa oleifera, a globally widespread [...] Read more.

Global warming has become a significant public health concern, with intensive livestock farming as a major contributor. To mitigate greenhouse gas emissions, strategies such as manipulating the ruminal environment with dietary additives are essential. This study evaluated Moringa oleifera, a globally widespread tree with antioxidant, multivitamin, protein-rich, and anti-inflammatory properties, as a feed additive. Rumen fluid was collected from three Pelibuey sheep, homogenized, and subjected to an in vitro fermentation study for 48 h with three alfalfa/moringa ratio treatments: T0 Control (100:0), T1 Low (85:15), and T2 High (70:30). Total RNA was extracted, followed by high-definition sequencing of the metatranscriptome. The sequencing yielded approximately 456 million sequences. A total of 117 phyla were identified and approximately 1300 genera were mapped. Predominant phylum differed by treatment: T0, Firmicutes; T1, Proteobacteria; and T2 with Synergistetes, at least one sample per treatment. Archaea were nearly absent in T1, which explains a statistically significant decrease in methane production. In the Gene Set Enrichment Analysis (GSEA), it was observed that one of the metabolic pathways with a statistically significant difference (p-value < 0.05) was that of methane, specifically in the low moringa treatment (T1) compared to the control (T0). From the functional analysis, differentially expressed enzymes were identified, some of which are involved in the methane metabolic pathway, such as formate dehydrogenase (EC 1.17.1.9) and glycine hydroxymethyltransferase (EC 2.1.2.1), which are intermediates in methane formation. These results suggest that 15% Moringa oleifera supplementation alters ruminal microbiota, reduces archaeal activity, and suppresses methane-related pathways. These findings provide molecular evidence supporting the potential of M. oleifera as a methane mitigation strategy in ruminant nutrition. Full article

(This article belongs to the Special Issue Ruminal Fermentation: 2nd Edition)

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18 pages, 825 KB

Open AccessArticle

Diet Formulated with Rice Bran Fermented by Rhizopus oryzae and Saccharomyces cerevisiae: Impacts on Zootechnical Performance and Intestinal Gene Expression in Zebrafish (Danio rerio)

by Gabriela Lenz, Rejane Macedo Martins, Jade Riet, Raíza dos Santos Azevedo, Arthur Cardoso, Bruna Félix da Silva Nornberg, Martín Bessonart, Larisa Magnone, Luis Fernando Fernandes Marins, Iuri Salim Abou Anni, Tatiane Penteado Gonçalves, Anelise Christ-Ribeiro and Marcelo Borges Tesser

Fermentation 2025, 11(10), 567; https://doi.org/10.3390/fermentation11100567 - 30 Sep 2025

Abstract

The growing demand for aquaculture has driven the search for sustainable practices and utilization of agro-industrial residues. Brown rice bran, an abundant and low-cost by-product, has emerged as a promising raw material. This dissertation aimed to evaluate solid-state fermentation (SSF) of rice bran [...] Read more.

The growing demand for aquaculture has driven the search for sustainable practices and utilization of agro-industrial residues. Brown rice bran, an abundant and low-cost by-product, has emerged as a promising raw material. This dissertation aimed to evaluate solid-state fermentation (SSF) of rice bran using the fungus Rhizopus oryzae and the yeast Saccharomyces cerevisiae with the goal of improving its nutritional value for use in diets formulated for zebrafish (Danio rerio). Proximate composition analyses revealed the strong biotransformation potential of Rhizopus oryzae. Fermentation with this fungus resulted in a significant 36.45% increase in protein content, a 51.62% increase in total polyphenols, and a 13.7% reduction in lipid content. In an in vivo experiment, zebrafish fed a diet containing rice bran fermented by R. oryzae showed the best zootechnical performance, with higher weight gain, specific growth rate, and improved feed conversion. Gene expression analysis showed a significant difference only for glut6, which is related to glucose transport. In summary, the fermentation of brown rice bran with Rhizopus oryzae represents an effective strategy to enhance its nutritional profile, establishing it as a viable alternative for the formulation of more sustainable and efficient diets in aquaculture. Full article

(This article belongs to the Special Issue Exploring Fermentation Strategies for the Valorization of Food By-Products and Their Bioactive Potential)

15 pages, 723 KB

Open AccessArticle

Biosafe Control of Staphylococcal Enterotoxins Production in Shelf-Stable Bacon

by Carlos Alberto Guerra, Edson Pinto Barboza Júnior, Letícia Guimarães de Oliveira Alves and André Fioravante Guerra

Fermentation 2025, 11(10), 566; https://doi.org/10.3390/fermentation11100566 - 30 Sep 2025

Abstract

This study proposed a biosafe strategy to prevent staphylococcal enterotoxin production in cooked bacon, particularly in microenvironments at the product–package interface that may favor toxinogenesis. Challenge tests were conducted on bacon samples with varying water activity, inoculated with Staphylococcus aureus, and treated [...] Read more.

This study proposed a biosafe strategy to prevent staphylococcal enterotoxin production in cooked bacon, particularly in microenvironments at the product–package interface that may favor toxinogenesis. Challenge tests were conducted on bacon samples with varying water activity, inoculated with Staphylococcus aureus, and treated with a biopreservative produced in an axenic cultivation of Lacticaseibacillus paracasei DTA-83. Staphylococcal enterotoxin production was assessed using an ELISA test. Data about microbial growth and staphylococcal enterotoxin production were evaluated under simulated storage using the MicroLab_ShelfLife protocol. Results showed that staphylococcal enterotoxin production occurred independently of water activity, indicating that it alone does not ensure microbial safety. Even at a water activity level traditionally considered inhibitory, enterotoxin formation was observed, emphasizing the critical role of the product–package interface. However, a 1.0% biopreservative applied to the product surface effectively inhibited S. aureus growth and completely suppressed staphylococcal enterotoxin production under all conditions, including temperature abuse. In conclusion, the formation of enterotoxin by S. aureus at low water activity reveals a critical safety risk at the product–package interface. Targeted application of a 1.0% biopreservative at this vulnerable site proved highly effective, reinforcing its role as a practical and non-intrusive hurdle strategy to enhance microbial safety in shelf-stable meat products. Full article

(This article belongs to the Special Issue Microbial Fermentation: A Sustainable Approach to Food Production)

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15 pages, 1213 KB

Open AccessArticle

Valorization of Mixed Lignocellulosic Biomass for Bioethanol Production Using Thermotolerant Yeast Saccharomyces cerevisiae SC90

by Malaika Amjad, Muhammad Abbas, Abdullah Langou, Imrana Niaz Sultan and Afrasiab Khan Tareen

Fermentation 2025, 11(10), 565; https://doi.org/10.3390/fermentation11100565 - 30 Sep 2025

Abstract

Bioethanol manifests an extraordinary potential to overcome the severe energy crises and reliance on fossil fuels, yet it supports the sustainable and cost-effective production of fuels for automobile engines and contributes to the reduction of greenhouse gas (GHG) emissions and other global climate-related [...] Read more.

Bioethanol manifests an extraordinary potential to overcome the severe energy crises and reliance on fossil fuels, yet it supports the sustainable and cost-effective production of fuels for automobile engines and contributes to the reduction of greenhouse gas (GHG) emissions and other global climate-related challenges. The present study examines the potential of Mixed Lignocellulosic Biomass (MLB) as a sustainable feedstock for the consistent year-round production of bioethanol. The primary MLB sources considered in this research to underscore the significance of this heterogeneous strategy include sweet sorghum bagasse (SSB), sugarcane bagasse (SCB), and date palm trunk (DPT). Each of the three feedstocks, i.e., SSB, SCB, and DPT, were individually subjected to alkaline pretreatment, a step aimed at breaking down structural barriers and facilitating greater release of fermentable sugars during fermentation. Likewise, the alkaline-pretreated biomasses were subjected to simultaneous saccharification and fermentation (SSF) for 96 h, both individually as well as in various combined proportions. Individually, pretreated sweet sorghum bagasse (SSB) fibers produced the highest ethanol concentration, of 30.79 ± 0.44 g/L; an ethanol yield of 0.40 ± 0.62 g/g; an ethanol productivity of 0.42 ± 0.87 g/L/h; and a theoretical ethanol yield of 79.81% at 72 h. In contrast, the combination of MLB (50% of pretreated SSB and 50% of DPT fibers) produced a significantly higher ethanol concentration of 31.47 ± 0.57 g/L and an ethanol productivity of 0.653 ± 0.24 g/L/h in much less time, i.e., 48 h of SSF fermentation. The empirical data confirms that MLB offers a sustainable paradigm for ethanol biosynthesis by curtailing fermentation time and optimizing economic and operational efficacy. Full article

(This article belongs to the Special Issue Lignocellulosic Biomass Valorisation, 2nd Edition)

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16 pages, 3569 KB

Open AccessArticle

Boosting Probiotic Biomass of Lactobacillus acidophilus CCFM137 Through pH-Stat Morphological Control and Medium Optimization

by Shao-Quan Yan, Yang-Yang Shi, Rui Yang, Rui Li, Feng Hang and Hao Zhang

Fermentation 2025, 11(10), 564; https://doi.org/10.3390/fermentation11100564 - 30 Sep 2025

Abstract

The fermentation performance of Lactobacillus acidophilus is constrained by factors such as low cell density and fastidious nutritional and environmental requirements, which greatly limit its industrial-scale applications. This study aimed to develop an efficient fermentation condition for L. acidophilus CCFM137 through systematic optimization [...] Read more.

The fermentation performance of Lactobacillus acidophilus is constrained by factors such as low cell density and fastidious nutritional and environmental requirements, which greatly limit its industrial-scale applications. This study aimed to develop an efficient fermentation condition for L. acidophilus CCFM137 through systematic optimization of both culture medium and environmental parameters, thereby enabling high-yield industrial-scale production of this strain. An optimized medium was developed, consisting of glucose (30 g/L), YEP FM503 (35 g/L), sodium acetate (5 g/L), ammonium citrate (2 g/L), K₂HPO₄ (2 g/L), MgSO₄·7H₂O (0.1 g/L), MnSO₄·H₂O (0.05 g/L), L-cysteine hydrochloride (0.5 g/L), and Tween 80 (1 mL/L), to achieve a viable cell count of 1.95 × 10⁹ CFU/mL, representing a 9.42-fold increase over that of standard MRS broth. Subsequent pH-stat fermentation trials in a 100 L fermenter using the optimized medium revealed morphological and growth characteristics of the strain in variable pH-stat environments. Optimal performance was observed under pH-stat 4.5 rather than the more commonly used 5.7, achieving maximum viable cell counts of 3.37 × 10⁹ CFU/mL, accompanied by a transformation of cell morphology toward shorter rod-shaped structures, as well as an increase in substrate utilization rate, cell recovery rate and lyophilization survival rate. The fermentation performance and cellular morphology of L. acidophilus CCFM137 were enhanced by both nutrient composition and pH environment. These results showed that this strategy has potential for application in high cell density fermentation of L. acidophilus CCFM137. Full article

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

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20 pages, 3126 KB

Open AccessReview

Integrated Pretreatment and Microbial Matching for PHA Production from Lignocellulosic Agro-Forestry Residues

by Dongna Li, Shanshan Liu, Qiang Wang, Xiaojun Ma and Jianing Li

Fermentation 2025, 11(10), 563; https://doi.org/10.3390/fermentation11100563 - 29 Sep 2025

Abstract

Lignocellulosic agro-forestry residues (LARs), such as rice straw, sugarcane bagasse, and wood wastes, are abundant and low-cost feedstocks for polyhydroxyalkanoate (PHA) bioplastics. However, their complex cellulose–hemicellulose–lignin matrix requires integrated valorization strategies. This review presents a dual-framework approach: “pretreatment–co-substrate compatibility” and “pretreatment–microbial platform matching”, [...] Read more.

Lignocellulosic agro-forestry residues (LARs), such as rice straw, sugarcane bagasse, and wood wastes, are abundant and low-cost feedstocks for polyhydroxyalkanoate (PHA) bioplastics. However, their complex cellulose–hemicellulose–lignin matrix requires integrated valorization strategies. This review presents a dual-framework approach: “pretreatment–co-substrate compatibility” and “pretreatment–microbial platform matching”, to align advanced pretreatment methods (including deacetylation–microwave integration, deep eutectic solvents, and non-sterilized lignin recovery) with engineered or extremophilic microbial hosts. A “metabolic interaction” perspective on co-substrate fermentation, encompassing dynamic carbon flux allocation, synthetic consortia cooperation, and one-pot process coupling, is used to elevate PHA titers and tailor copolymer composition. In addition, we synthesize comprehensive kinetic analyses from the literature that elucidate microbial growth, substrate consumption, and dynamic carbon flux allocation under feast–famine conditions, thereby informing process optimization and scalability. Microbial platforms are reclassified as broad-substrate, process-compatible, or product-customized categories to emphasize adaptive evolution, CRISPR-guided precision design, and consortia engineering. Finally, next-generation techno-economic analyses, embracing multi-product integration, regional adaptation, and carbon-efficiency metrics, are surveyed to chart viable paths for scaling LAR-to-PHA into circular bioeconomy manufacturing. Full article

(This article belongs to the Special Issue The Future of Fermentation Technology in the Biorefining Process: 3rd Edition)

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17 pages, 987 KB

Open AccessArticle

Bioemulsifier Produced by Aspergillus niger UCP 1064 Isolated from Caatinga Soil as a Promising Molecule for Scaled-Up Pharmaceutical Applications

by Uiara Maria de Barros Lira Lins, Rosileide Fontenele da Silva Andrade and Galba Maria de Campos-Takaki

Fermentation 2025, 11(10), 562; https://doi.org/10.3390/fermentation11100562 - 29 Sep 2025

Abstract

This study presents the production, characterization, and potential pharmaceutical application of a bioemulsifier synthesized by Aspergillus niger UCP 1064 by submerged fermentation using agro-industrial residues (cassava wastewater and soluble starch). The compound exhibited a high emulsification index (EI₂₄ > 88%) against hydrophobic [...] Read more.

This study presents the production, characterization, and potential pharmaceutical application of a bioemulsifier synthesized by Aspergillus niger UCP 1064 by submerged fermentation using agro-industrial residues (cassava wastewater and soluble starch). The compound exhibited a high emulsification index (EI₂₄ > 88%) against hydrophobic substrates, effectively reduced surface tension, and remained stable across a wide range of pH (2–12), temperatures (5–100 °C), and salinity levels (0–20% NaCl). Microscopic analysis confirmed the formation of stable oil-in-water (O/W) emulsions, while biochemical tests identified the compound as a glycolipoprotein. Rheological assays demonstrated a significant reduction in oil viscosity, enhancing fluidity. Through factorial design and response surface methodology, production conditions were optimized, achieving yields of up to 3.18 g/L. A theoretical scale-up indicated technical feasibility for pharmaceutical applications; however, challenges such as process reproducibility, sterility, and regulatory compliance persist. These findings highlight the bioemulsifier’s potential as a sustainable and biocompatible alternative for drug delivery systems. Full article

(This article belongs to the Special Issue Scale-Up Challenges in Microbial Fermentation)

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16 pages, 1477 KB

Open AccessArticle

Valorization of Oat Husk for the Production of Fermentable Sugars, Xylooligosaccharides, and Inulinase via Deep Eutectic Solvent and Microwave-Assisted Pretreatment

by Hatice Gözde Hosta Yavuz, Ibrahim Yavuz and Irfan Turhan

Fermentation 2025, 11(10), 561; https://doi.org/10.3390/fermentation11100561 - 28 Sep 2025

Abstract

This study presents an integrated valorization strategy for oat husks through microwave-assisted pretreatment using a deep eutectic solvent (DES) composed of choline chloride and glycerol (1:2). The process was designed to enhance the release of fermentable sugars, enable xylooligosaccharide (XOS) production, and support [...] Read more.

This study presents an integrated valorization strategy for oat husks through microwave-assisted pretreatment using a deep eutectic solvent (DES) composed of choline chloride and glycerol (1:2). The process was designed to enhance the release of fermentable sugars, enable xylooligosaccharide (XOS) production, and support inulinase production by Aspergillus niger A42 via submerged fermentation of the hydrolysate and solid-state fermentation of the residual biomass. Response surface methodology (RSM) was applied to evaluate the effects of microwave power, treatment time, and liquid-to-solid ratio (LSR) on fermentable sugar content (FSC) and total phenolic compounds (TPCs). Following pretreatment, the biomass was hydrolyzed using 1.99% sulfuric acid for 1 min. Optimal pretreatment conditions (350 W, 30 s, LSR 4 w/w) yielded an FSC of 51.14 g/L. Additionally, 230.78 mg/L xylohexaose and 6.47 mg/L xylotetraose were detected. Submerged fermentation of the liquid fraction with A. niger A42 resulted in inulinase and invertase activities of 60.45 U/mL and 21.83 U/mL, respectively. Solid-state fermentation of the pretreated solids produced 37.03 U/mL inulinase and 17.64 U/mL invertase. The integration of microwave-assisted DES pretreatment, dilute acid hydrolysis, and fungal fermentation established a robust strategy for the sequential production of XOS, fermentable sugars, and inulinase from oat husks, supporting their comprehensive utilization within a sustainable biorefinery framework. 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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