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Fermentation

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

Quartile Ranking JCR - Q2 (Biotechnology and Applied Microbiology)

All Articles (4,013)

3-Amino-4-hydroxybenzoic acid (3,4-AHBA) is a non-proteinogenic aromatic compound that functions as a key biosynthetic precursor for diverse secondary metabolites with pharmaceutical and industrial value. Microbial production of 3,4-AHBA offers a sustainable alternative to petroleum-based chemical synthesis; however, metabolic complexity and trade-offs between growth and product formation constrain rational strain design. Here, genome-scale metabolic (GSM) modeling and flux balance analysis (FBA) were integrated with targeted genetic engineering to elucidate and enhance 3,4-AHBA production in Streptomyces thermoviolaceus. A genome-scale metabolic model was constructed and expanded by incorporating the nspH–nspI gene operon, which encodes the 3,4-AHBA biosynthetic pathway. In silico FBA predicted substantial rewiring of central carbon metabolism, with carbon flux redirected from glycolysis and the tricarboxylic acid cycle toward aspartate-derived intermediates and 3,4-AHBA synthesis, accompanied by reduced biomass-associated flux. Guided by these predictions, an engineered strain (St::NspHI) was developed and experimentally evaluated. Consistent with model predictions, the engineered strain exhibited lower growth rates and glucose uptake than the wild type, reflecting a metabolic burden. Nevertheless, 3,4-AHBA production was achieved exclusively in the engineered strain. Comparison of simulated and experimental fluxes revealed overestimation by FBA, likely due to secondary metabolism and incomplete genome annotation. Overall, GSM-guided design enables optimization of precursor production.

12 February 2026

Predicted metabolic pathways and intracellular flux distributions for 3-amino-4-hydroxybenzoic acid (3,4-AHBA) production in S. thermoviolaceus. The figure illustrates alterations in central carbon metabolism following insertion of the nspH–nspI gene operon. Red arrows highlight the engineered biosynthetic route toward 3,4-AHBA and key modified reactions. Flux values calculated by flux balance analysis (FBA) are indicated next to each reaction, with black numbers representing the wild-type strain and red numbers representing the St::NspHI strain. All fluxes are expressed in mmol gDCW−1 h−1. Flux distributions were calculated under aerobic conditions with growth rates constrained to experimentally determined values.

The rapid growth of the global population and the impending depletion of fossil fuels, currently meeting approximately 80% of the world’s power needs, have intensified interest in biofuels derived from renewable biomass. This editorial refers to the Special Issue, “Biofuel Production and Processing Technology, 3rd Edition,” which highlights the transition of fermentation-based technologies from isolated processes into integrated, multifunctional biorefinery platforms. The collection includes nine contributions (eight original articles and one review) covering diverse advancements, including: The valorization of industrial intermediates, strategies to improve anaerobic digestion through co-digestion and heat recovery integration, mechanistic insights into syngas fermentation and the development of multi-product microbial systems, emerging frontier technologies, such as biological hydrogen production in depleted oil and gas reservoirs. Collectively, these studies emphasize that the future of sustainable energy relies on system-level optimization, balancing feedstock flexibility, energy integration, and environmental performance within a circular bioeconomy.

12 February 2026

This study aimed to determine the effects of incorporating probiotic fermented natural lactic acid bacteria (PFJ) into the drinking water of laying quails subjected to temperature stress on egg production, egg quality, cecum microbiology, blood parameters, and incubation performance. A total of 260 Japanese quails (Coturnixcoturnix japonica) aged 8 weeks were used, of which 200 were females, and 60 were males. The quails were divided into four groups, each containing 50 individuals, and further split into five subgroups of 10 quails. For every 10 female quails, three male quails were housed together in cages. The experiment was conducted under normal environmental conditions in control, PFJ, heat-stressed control, and heat-stressed PFJ groups. Temperature stress (34–36 °C) was applied for 8 h daily. The results indicated that by the end of weeks 1–4, the feed conversion ratios of all groups were significantly different, with the best feed conversion ratio of 2.36 found in the PFJ group under temperature stress. Throughout the periods of weeks 1–4 and 5–8, there were statistically significant differences (p < 0.01) in the daily average feed consumption and egg weights among all treated groups. Temperature stress and the addition of PFJ significantly affected shell thickness, Haugh units, albumen weight, yolk weight, and yolk color; no significant impacts were observed on egg shape index, yolk percentage (%), albumen percentage (%), and specific gravity (g/cm3). The highest counts of lactic acid bacteria (LAB) were found in the PFJ-treated groups under both normal and temperature-stressed conditions. Under temperature stress, the levels of Enterobacter, coliform, and E. coli decreased with the addition of PFJ. Regarding blood parameters, significant differences (p < 0.05) were observed in total protein values among groups, while differences in chloride, triglycerides, total cholesterol, LDL cholesterol, HDL cholesterol, and triglyceride concentrations were not statistically significant (p > 0.05). Furthermore, the addition of temperature stress and PFJ significantly affected fertility rates, incubation efficiency, and hatchability. In conclusion, these findings suggest that PFJ could be considered a potential probiotic alternative for improving nutrition in laying quails under conditions of temperature stress.

12 February 2026

This study aimed to evaluate the effects of mixed strain fermentation on the microbial diversity, fermentation quality, and flavor of corn gluten meal-based fermented feed (CGMFF). High-throughput sequencing techniques (16S rDNA and ITS) and GC-MS technology were used to determine microbial community succession and flavor changes during the fermentation and storage stages of CGMFF and to explore their correlations. The results showed that Xeromyces and Lactobacillus became the dominant genera at the end of storage, with a relative abundance exceeding 96%. During fermentation and storage, the contents of soluble protein and ammonia nitrogen increased while the crude protein content decreased. The protein molecular weight was concentrated in the range of 75–1100 Da (96.98%), and the free amino acid (FAA) content increased by 1.42 times. This reduction in the proportion of bitter amino acids enhanced the palatability of CGMFF. The aroma gradually developed characteristics dominated by esters and alkanes. This study is intended to provide a theoretical basis for the application of corn gluten meal as a protein-rich raw material in fermented feed.

12 February 2026

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Fermentation Processes
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Fermentation Processes

Modeling, Optimization and Control: 2nd Edition
Editors: Ricardo Aguilar-López
Advances in Analysis of Flavors and Fragrances
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Advances in Analysis of Flavors and Fragrances

Chemistry, Properties and Applications in Food Quality Improvement
Editors: Ana Leahu, Maria Soledad Prats Moya, Cristina Ghinea

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Fermentation - ISSN 2311-5637