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PubMed1976

Photodynamic action of thiopyronine on the respiration and fermentation in yeast.

The efficiency of photodynamic treatment with thiopyronine (TP) on the respiration and fermentation of yeast cells, on the metabolic oxygen uptake of isolated mitochondrial preparations from yeast, and on the enzyme activity of alcohol dehydrogenase (ADH) in vivo and in vitro were studied. Respiration was inactivated by treatment with TP and visible light more at the initial stage than was the fermentation. Isolated mitochondria and ADH in vitro were not as sensitive to treatment as were respiration and fermentation in vivo. Inactivation patterns of respiration and fermentation in vivo showed that the inactivation was not due to damage to the DNA. The hindrance of respiration and fermentation might be one of main causes of cell-death resulting from photodynamic treatment.

Alcohol Oxidoreductases↗
PubMed1979

Fermentations by saccharolytic intestinal bacteria.

Most nonsporing anaerobes of the intestinal tract use the Embden-Meyerhof-Parnas scheme to ferment carbohydrates. Almost all of them oxidize pyruvate, the key fermentation intermediate, to acetyl coenzyme A and CO2 with reduction of a low-potential electron acceptor. H2 is formed from the low potential acceptor or from NADH. Pyruvate is a precursor of lactate, and phosphoenolpyruvate is a precursor of succinate and propionate. Ethanol, acetate, and butyrate are formed from acetyl coenzyme A. Formate is produced by reduction of CO2 by Ruminococcus albus. Heme is required by human Bacteroides for the formation of succinate and, in the presence of vitamin B12, propionate. A fermentation equation derived from the concentration of volatile acids found in human feces suggests that the fermentation in the large intestine is similar to the rumen fermentation.

Actinomycetales↗
PubMed1977

Fermentation of L-aspartate by a saccharolytic strain of Bacteroides melaninogenicus.

Resting cells of Bacteroides melaninogenicus fermented L-[14C]aspartate as a single substrate. The 14C-labeled products included succinate, acetate, CO2, oxaloacetate, formate, malate, glycine, alanine, and fumarate in the relative percentages 68, 15, 9.9, 2.7, 1.8, 1.0, 0.7, 0.5, and 0.06, respectively, based on the total counts per minute of the L-[14C]aspartate fermented. Ammonia was produced in high amounts, indicating that 96% of the L-aspartate fermented was deaminated. These data suggest that L-aspartate is mainly being reduced through a number of intermediate reactions involving enzymes of the tricarboxylic acid cycle to succinate. L-[14C]asparagine was also fermented by resting cells of B. melaninogenicus to form L-aspartate, which was subsequently, but less actively, fermented.

Amino Acids↗
PubMed1977

Fermentation of mucin and plant polysaccharides by strains of Bacteroides from the human colon.

Ten Bacteroides species found in the human colon were surveyed for their ability to ferment mucins and plant polysaccharides ("dietary fiber"). A number of strains fermented mucopolysaccharides (heparin, hyaluronate, and chondroitin sulfate) and ovomucoid. Only 3 of the 188 strains tested fermented beef submaxillary mucin, and none fermented porcine gastric mucin. Many of the Bacteroides strains tested were also able to ferment a variety of plant polysaccharides, including amylose, dextran, pectin, gum tragacanth, gum guar, larch arabinogalactan, alginate, and laminarin. Some plant polysaccharides such as gum arabic, gum karaya, gum ghatti and fucoidan, were not utilized by any of the strains tested. The ability to utilize mucins and plant polysaccharides varied considerably among the Bacteroides species tested.

Bacteroides↗
PubMed1975

Fungal growth and acid production during fermentation and refermentation of organic acid treated corn silages.

Chopped corn (35% dry matter) treated with either propionic, formic, 60% propionic plus 40% formic, or 80% propionic plus 20% acetic acids at 0, .5, 1, and 2%, was placed in polyethylene bags inside metal drums, and evacuated. During fermentation silages were sampled and temperatures determined. On day 40 of fermentation silages were placed in open containers at 25 C and were sampled during refermentation. All samples were analyzed for volatile and lactic acids, pH, and number and type of fungi. Lactate fermentation was totally inhibited at 2% addition of all acids, but formic acid was more effective than propionic acid at .5 and 1%. Acerate production was equally depressed by both propionic and formic additions. Heating, growth of fungi, and days until spoilage were delayed by all acid additions during refermentation, with propionic more effectivethan formic. The large increases in lactate and acetate of treated silages during refermentation reflect a protection of soluble sugars during fermentation and subsequent use by microbes after exposure to air. Silages treated with more than 1%propionic (as propionic or a mixture) did not increase in fungal colonies during refermentation. At initiation of fermentation yeasts werehigher than other fungi but decreases by day 40. During refermentation, yeasts again grew. Geotrichum comprised 35% on day 40 of refermentation but was lower at other times. Aspergillus proliferated during refermentation and few Penicillium were detected.

Acetates↗
PubMed1976

Protein, methionine, lysine and a fermentation residue as variables in diets of young turkeys.

A study was conducted to determine the effects of adding methionine, lysine and a fermentation residue to practical-type diets containing 24, 27, and 30% protein for young turkeys. A 2 X 2 X 2 X 3 factorial design of variables was used in each of two seven-week experiments. A total of 864 poults were divided into groups such that the 24 diets were each fed to 9 males and 9 females in each experiment. Seven-week body weights were increased 11.4% from 0.1% added DL-methionine and decreased 13.7% from 1.5% added fermentation residue, L-Lysine added at 0.157% failed to increase significantly body weights. Increasing the protein from 24 to 27 and 30% increased seven-week body weights 16.7 and 28.9%, respectively. As dietary protein increased, the increases in body weight from added methionine became smaller, i.e., 16.9, 14.4 and 4.8% in diets containing 24, 27, and 30% protein, respectively. Plots of body weight on (1) amount of methionine and on (2) amount of total sulfur amino acids in the diet show a closer relationship with the latter. The sulfur amino acid requirement of poults to seven weeks of age appears to be at least 1.03%, the highest quantity used in this study. The fermentation residue, a product not currently marketed, remains after the isolation of spectinomycin from controlled fermentation of Streptomyces flavopersicus and contains 14% dry matter. The cause of the depressed growth from the added fermentation residue has been discussed.

Animal Feed↗
PubMed1977

[Fecal fermentation in meteorism].

An old test to investigate fecal fermentation was modified with the purpose of changing it from qualitative to quantitative. The modified test consists in placing in stove, at 37 degrees C for 24 hours, 5 grams of feces, suspended in water. The fermentable alimentary residues, present in the feces, suffer the action of bacteria, also there present, yielding gas that is collected and measured. Using the test, fecal fermentation was determined in 3 groups of individuals: a) 40 patients with meteorism that had persisted or improved only slightly or fairly with treatment; b) 28 apparently healthy subjects; and c) 6 patients with meteorism that had disappeared or become minimal with treatment. In the group of 28 apparently healthy subject, the obtained results varied from 0.1 to 1.1 ml gas/24 h., with a mean +/- s.d. of 0.55 +/- 0.29 ml. gas/24 h. When a distribution curve was made with the results obtained in the group of 40 patients with meteorism, these results separated into 2 subgroups: one subgroup with 28 patients, in whom results varied from 1.0 to 13.3 ml. gas/24 h., with a mean of 4.8 gas/24 h. (only) in 1 of these 28 patients a normal result of 1.0 ml. gas/24 h. was obtained, while in the remaining 27 patients results of 1.5 or more ml. gas/24 h. were obtained); and the other subgroup with 12 patients, in whom results varied from 0.0 to 0.9 ml. gas/24 h., with a mean of 0.29 ml. gas/24 h. Finally, in the group of 6 patients with successfully treated meteorism, results were from 0.1 to 0.9 ml. gas/24 h., with a mean of 0.4 ml. gas/24 h. The above mentioned results strongly suggest the existence of a relationship between meteorism and exagerated fecal fermentation. The nature of this relationship has not yet been completely clarified. However, the test used to determine fecal fermentation already promises to be very helpful for a better understanding and management of meteorism.

Adult↗
PubMed2026

Microbial diversity, functional activities, and safety risks in fermented tea: a comprehensive review.

Microbial fermented teas are gaining global popularity due to their unique sensory profiles and health benefits. The quality and safety of these products are governed by complex microbial ecosystems that orchestrate the biotransformation of tea leaf components. This review addresses a critical paradox in the field: the same microbial activities that generate desirable bioactive metabolites, such as theabrownins and organic acids, also create ecological niches for mycotoxigenic fungi, posing significant health risks from contaminants like ochratoxin A, citrinin, and aflatoxins. While extensive research has cataloged the microbial diversity in these systems, a comprehensive framework linking processing environments to microbial community assembly, functional outcomes, and quantifiable safety risks remains elusive. This review systematically bridges this gap by synthesizing current knowledge on the microbial consortia-dominated by Aspergillus, Penicillium, Bacillus, and Lactiplantibacillus species-that drive tea fermentation. We critically analyze their functional roles in enhancing flavor, bioactivity, and potential probiotic activity while simultaneously evaluating the mechanisms of mycotoxin production and accumulation. By integrating microbial ecology, biochemistry, and food safety, we propose a forward-looking perspective focused on transitioning the industry from traditional, spontaneous fermentation to modern, controlled biotechnological processes. This approach, centered on the use of defined starter cultures, predictive modeling, and active biocontrol strategies, provides a roadmap for ensuring the consistent quality and safety of fermented tea products, ultimately unlocking their full potential as high-quality functional foods.

Tea↗
PubMed2024

Salmonella Typhimurium screen identifies shifts in mixed-acid fermentation during gut colonization.

How enteric pathogens adapt their metabolism to a dynamic gut environment is not yet fully understood. To investigate how Salmonella enterica Typhimurium (S.Tm) colonizes the gut, we conducted an in vivo transposon mutagenesis screen in a gnotobiotic mouse model. Our data implicate mixed-acid fermentation in efficient gut-luminal growth and energy conservation throughout infection. During initial growth, the pathogen utilizes acetate fermentation and fumarate respiration. After the onset of gut inflammation, hexoses appear to become limiting, as indicated by carbohydrate analytics and the increased need for gluconeogenesis. In response, S.Tm adapts by ramping up ethanol fermentation for redox balancing and supplying the TCA cycle with α-ketoglutarate for additional energy. Our findings illustrate how S.Tm flexibly adapts mixed fermentation and its use of the TCA cycle to thrive in the changing gut environment. Similar metabolic wiring in other pathogenic Enterobacteriaceae may suggest a broadly conserved mechanism for gut colonization.

Animals↗
PubMed2026

Viral community in Aspergillus spp. isolated from commercially available fermented dried bonito.

Katsuobushi is a traditional processed seafood product used in Japanese-style cooking, and when it is produced through fermentation by fungi, it is called karebushi. The fungi involved in katsuobushi fermentation are collectively referred to as katsuobushi molds. We previously discovered seven novel viruses from katsuobushi molds and determined their genome sequences. However, our previous explorations used only nine fungal strains available from culture collections, leaving the diversity of viruses infecting fungi involved in katsuobushi fermentation unclear. Therefore, in this study, we aimed to isolate fungi from commercially available karebushi and clarify the prevalence of viruses in the isolates. Karebushi produced by three manufacturers was obtained, and 30 fungal strains (including Aspergillus spp.) were isolated from each. Double-stranded RNA (dsRNA) fractions were prepared from the mycelia of the isolated strains. Electrophoresis suggested that a relatively high proportion of the isolates harbored dsRNA elements consistent with RNA virus infection (30-70% per manufacturer; 59% overall). Furthermore, dsRNA sequencing identified four novel viruses in isolates of Aspergillus chevalieri and Aspergillus montevidensis: a beny-like virus, a gammapartitivirus, a narnavirus, and a victorivirus, in addition to two previously reported viruses. Notably, this represents the first report of a beny-like virus in Aspergillus spp. This study provides insights into the diversity of viruses infecting fungi involved in katsuobushi fermentation.

Aspergillus↗
PubMed2026

Transcriptomic shift in ethanol and amino acid metabolic genes regulated by Med15 during alcoholic fermentation.

Organisms that thrive in extreme environments provide natural experiments in evolution, revealing the genetic regulators that orchestrate complex phenotypic change. Wine yeast (WY) are specialized strains that are adapted to survive in the wine making environment while producing high concentrations of ethanol. In addition to large genomic changes that differentiate WY from yeast used in other industries, SNP and polyglutamine tract polymorphism in the transcriptional regulator Med15 are associated with the fermentation efficiency and stress response phenotypes of WY. In this study, we investigated the transcriptional differences during wine fermentation in transgenic lab strain yeast having integrated WY MED15 alleles. Compared to the unmodified lab strain (MED15 LAB), the same strain in which the MED15 locus was replaced with a MED15 allele from yeast isolated from palm wine, the fermented sap of palm (oil, date, coconut) trees (MED15 WY23), exhibited enhanced expression of amino acid biosynthesis genes as well as stress resistance and metabolic adaptation genes. Our experimental data confirm the role of arginine in efficient fermentation and suggest that certain MED15 alleles alter the expression patterns of arginine pathway genes in some cases improving carbon flux under nitrogen stress. The global benefits conferred by natural polymorphisms in a single transcriptional regulator highlight Med15 as a target for engineering of strains devoted to various types of alcohol production.

Ethanol↗
PubMed1977

Computer-aided baker's yeast fermentations.

The economics of yeast production depend heavily upon the cellular yield coefficient on the carbon source and the volumetric productivity of the process. The application of an on-line computer to maximize these two terms during the fermentation requires a continuous method of measuring cell density and growth rate. Unfortunately, a direct sensor for biomass concentration suitable for use in industrial fermentations is not available. Material balancing, with the aid of on-line computer monitoring, offers an indirect method of measurement. Laboratory results from baker's yeast production in a 14-liter fermentor (with a PDP-11/10 computer for on-line analyses) show this indirect measurement technique to be a viable alternative. From the oxygen uptake and carbon dioxide production data, gas flow rate, and ammonia addition rate, the cell density during the fermentation has been estimated and found to compare well with actual fermentation data.

Ammonia↗
PubMed1979

Application of balancing methods in modeling the penicillin fermentation.

This paper shows the application of elementary balancing methods in combination with simple kinetic equations in the formulation of an unstructured model for the fed-batch process for the production of penicillin. The rate of substrate uptake is modeled with a Monod-type relationship. The specific penicillin production rate is assumed to be a function of growth rate. Hydrolysis of penicillin to penicilloic acid is assumed to be first order in penicillin. In simulations with the present model it is shown that the model, although assuming a strict relationship between specific growth rate and penicillin productivity, allows for the commonly observed lag phase in the penicillin concentration curve and the apparent separation between growth and production phase (idiophase-trophophase concept). Furthermore it is shown that the feed rate profile during fermentation is of vital importance in the realization of a high production rate throughout the duration of the fermentation. It is emphasized that the method of modeling presented may also prove rewarding for an analysis of fermentation processes other than the penicillin fermentation.

Chemical Phenomena↗
PubMed2026

Integrated ¹H-NMR Metabolomics and Growth Kinetics Uncover Three Distinct Metabolic Scenarios in Lactiplantibacillus pentosus P7 Fermentation of Plant-Derived Prebiotics.

Lactic acid bacteria (LAB) drive a broad range of food and biotechnological fermentations, the outcomes of which depend not only on the bacterial genotype but also on the chemical composition of the fermentation substrate. To resolve how a single strain reorganises chemically distinct plant matrices, we profiled fermentations of Lactiplantibacillus pentosus P7 (GenBank JBLMKZ000000000) on garlic, onion, and kiwifruit extracts prepared in water and 70% ethanol, using growth kinetics combined with solvent-suppressed 500-MHz proton nuclear magnetic resonance metabolomics over 48 h, and integrated the data with whole-genome pathway annotations. Three substrate-specific metabolic scenarios emerged. On garlic, P7 grew vigorously, with the water extract exceeding the de Man-Rogosa-Sharpe reference medium at every time point (peak ΔOD₆₀₀ of 9.38 versus 8.52 at 24 h) and accumulating sorbose, rhamnose, and the aromatic amino acids phenylalanine and tryptophan (3.04- to 3.70-fold increases), providing first metabolic evidence consistent with the strain's four-copy aroE shikimate-dehydrogenase expansion. On onion, the lowest cell density coincided with the highest lactate output of the dataset (5.21-fold rise at 48 h), transient 5-hydroxymethylfurfural reduction, and accumulation of acetoin and 1,3-propanediol, mapping onto a redundant set of pyridine-nucleotide-dependent oxidoreductases and a pdu-independent diol pathway. On kiwifruit, citrate accumulated 8.9-fold at 16 h and then declined, consistent with an intact citCDEFG citrate-lyase operon paired with absence of canonical oxidative tricarboxylic acid enzymes. The optimal extraction solvent was substrate-dependent, water for garlic and ethanol for onion and kiwifruit. Overall, these results show that substrate chemistry, rather than strain identity, dictates which genome-encoded pathways P7 engages, establishing P7 as a versatile, substrate-tunable platform for the functional fermentation and biorefining of furanic-rich substrate streams. Raw NMR data and ISA-Tab metadata are available via MetaboLights with identifier MTBLS14463.

Lactiplantibacillus pentosus↗
PubMed2026

Adaptive laboratory evolution enables carbon-negative mixotrophic fermentation and enhanced chain elongation in Clostridium sp. JS66.

Improving carbon recovery during sugar fermentation remains a major challenge because a substantial fraction of substrate carbon is lost as CO2 during central metabolism. To overcome this limitation, Clostridium sp. JS66 (JS66), an acetogen producing hexanoic acid from glucose, was subjected to adaptive laboratory evolution under autotrophic CO2/H2 conditions to enhance H2-assisted CO2 reassimilation during glucose fermentation. The evolved strain, ALECO2, exhibited CO2 consumption without a lag phase under autotrophic conditions and reached a 9.5-fold higher CO2 uptake rate than JS66. Under fed-batch mixotrophic conditions, glucose-only fermentation yielded a carbon molar yield (Cmetabolite/Csugar, CM/CS) of 0.60, whereas H2 supplementation increased CM/CS to 0.91 and redirected carbon flux toward C6 products (hexanoic acid and hexanol), which accounted for 49% of total C_output. With additional CO2 supplementation, ALECO2 further assimilated externally supplied CO2, increasing the CM/CS to 1.10 and demonstrating carbon-negative fermentation. Assimilation of externally supplied CO2 further redirected carbon flux toward chain elongation, producing 7.14 g/L hexanoic acid and increasing the C6 carbon fraction to 57% of total C_output. Constraint-based flux analysis supported increased acetyl-CoA formation through the Wood-Ljungdahl pathway and enhanced flux toward reverse β-oxidation under H2- and CO2/H2-supplemented conditions. Genome analysis identified mutations including genes encoding a putative HytB homolog and a LysR-type transcriptional regulator. These results establish ALECO2 as a promising evolved anaerobic non-photosynthetic (ANP) mixotrophy platform that links CO2 reassimilation and external CO2 assimilation with chain elongation, enabling carbon-neutral and carbon-negative production of value-added C6 products from glucose.

Anaerobic non-photosyntheticmixotrophy (ANP)↗
PubMed2026

Integrated GC-HRAM-MS and UHPLC-QTOF-MS metabolomics reveal mineral-induced metabolic adaptation of Lactiplantibacillus pentosus 9D3 during milk fermentation.

Milk fermentation by plant-associated probiotic strains is constrained by poor adaptation to dairy matrices. This study evaluated genome-guided micronutrient supplementation to improve the performance and metabolomic profile of Lactiplantibacillus pentosus 9D3 in milk. Individual supplementation with Mn2+ or Mg2+ significantly enhanced bacterial growth and acidification, whereas Fe2+, Zn2+, and B-group vitamins showed limited effects. Optimal supplementation with 50 mg/L Mn2+ and 100 mg/L Mg2+ increased viable counts from 7.54 to 8.89 log CFU/mL. A cell population increase of ∼1.9 log CFU/mL was achieved despite reducing the inoculum level from 10% to 6%. Integrated metabolomic profiling using GC-HRAM-MS and UHPLC-QTOF-MS identified 299 metabolites across supplemented fermented milk, non-supplemented fermented milk, and unfermented milk, with group separation. Pathway analysis revealed significant enrichment of seven metabolic pathways, including purine, pyrimidine, galactose, propanoate, butanoate, amino sugar and nucleotide sugar, and α-linolenic acid metabolism. These findings support cost-efficient precision fermentation of functional dairy products.

Dairy products↗
PubMed2026

Multi-omics insights into aroma formation in congou black tea during fermentation.

This study used multi-omics technologies to analyze aroma formation during Congou black tea fermentation. Volatile compounds were analyzed by headspace solid phase microextraction coupled with gas chromatography mass spectrometry using two columns of different polarity. Fermentation increased total volatile normalized peak area fivefold, with alcohols, aldehydes, and acids increasing over sevenfold. 29 differential metabolites were screened, including amino acid derived phenylacetaldehyde, phenylethanol, and 2-methylbutanal; fatty acid derived (E,E)-2,4-heptadienal, hexanal, and 1-hexanol; and isoprenoid derived linalool, geraniol, and beta ionone. Transcriptomic, proteomic, and enzyme analyses revealed that biosynthesis contributed to early accumulation of amino acid and isoprenoid derived aromas, whereas ortho quinone mediated Strecker degradation and free radical induced fatty acid auto oxidation dominated generation of amino and fatty acid derived aromas during middle and late fermentation. In conclusion, aroma formation during fermentation results from biosynthesis and non-enzymatic oxidation, with the latter possibly dominating amino and fatty acid derived aromas.

Fermentation↗
PubMed1975

Effects of betel nut and fermented fish on the thiamin status of northeastern Thais.

Thiamin deficiency could result either from inadequate intake of thiamin or consumption of food containing antithiamin factors. Dietary surveys conducted in northeastern Thailand indicated that both thiamin and caloric intake of subjects under studies were sufficient. In Thailand, correlation exists between the consumption of food containing antithiamin factors and the prevalence of thiamin deficiency. Betel nuts and raw fermented fish possess antithiamin activity. Abstention from both betel nut chewing and raw fermented fish consumption resulted in a significant reduction of thiamin pyrophosphate effect. The thiamin pyrophosphate effect again increased significantly when the subjects resume their chewing habits. Cooking of fermented fish destroyed thiaminase, resulted in a significant decrease of thiamin pyrophosphate effect of the subjects. Thiamin supplementation (10 mg/day) could further reduce their thiamin pyrophosphate effect. This amount of thiamin could counteract the effect of raw fermented fish consumption but was not sufficient to neutralize the effect of betel nut chewing.

Adolescent↗