Search Results (301)

Plant-based fermented foods are increasingly promoted for glycemic control, yet their mechanisms and clinical impact remain incompletely defined. This narrative review synthesizes mechanistic, preclinical, and human data for key matrices—kimchi and other fermented vegetables, tempeh/miso/natto, and related legume ferments, kombucha and fermented teas, plant-based kefir, and cereal/pulse sourdoughs. Across these systems, microbial β-glucosidases, esterases, tannases, and phenolic-acid decarboxylases remodel polyphenols toward more bioaccessible aglycones and phenolic acids, while lactic and acetic fermentations generate organic acids, exopolysaccharides, bacterial cellulose, γ-polyglutamic acid, γ-aminobutyric acid, and bioactive peptides. We map these postbiotic signatures onto proximal mechanisms—α-amylase/α-glucosidase inhibition, viscosity-driven slowing of starch digestion, gastric emptying and incretin signaling, intestinal-barrier reinforcement, and microbiota-dependent short-chain–fatty-acid and bile-acid pathways—and their downstream effects on AMPK/Nrf2 signaling and the gut–liver axis. Animal models consistently show improved glucose tolerance, insulin sensitivity, and hepatic steatosis under fermented vs. non-fermented diets. In humans, however, glycemic effects are modest and highly context-dependent: The most robust signal is early postprandial attenuation with γ-PGA-rich natto, strongly acidified or low-glycemic sourdough breads, and selected kombucha formulations, particularly in individuals with impaired glucose regulation. We identify major sources of heterogeneity (starters, process parameters, substrates, background diet) and safety considerations (sodium, ethanol, gastrointestinal symptoms) and propose minimum reporting standards and trial designs integrating metabolomics, microbiome, and host-omics. Overall, plant-based ferments appear best positioned as adjuncts within cardiometabolic dietary patterns and as candidates for “purpose-built” postbiotic products targeting early glycemic excursions and broader metabolic risk. Full article

Robust yeast tolerance to inhibitors is essential for lignocellulosic biorefinery. Although cell flocculation is known to enhance acetic acid stress tolerance, the impact of its intensity remains unclear. In this study, engineered S. cerevisiae strains with distinct floc sizes were constructed through promoter engineering. The native FLO1 promoter in the non-flocculating laboratory strain BY4741 was replaced with either the constitutive strong promoter PGK1p or the ethanol-inducible promoter TPS1p using CRISPR-Cas9-mediated genome editing, resulting in strongly and moderately flocculating strains BY4741 PGK1p-FLO1 and BY4741 TPS1p-FLO1, respectively. It was revealed that the BY4741 PGK1p-FLO1 showed a survival advantage in the late-stage fermentation and severe stress condition in the presence of 7.5 g/L acetic acid, while BY4741 TPS1p-FLO1 exhibited superior growth and fermentation performance under 5.0 g/L acetic acid stress. Further studies suggested that the enhanced acetic acid tolerance in flocculating cells was associated with their ability to maintain significantly higher intracellular ATP levels under stress. Our work highlights the importance of optimizing flocculation properties for robust industrial fermentation, and also provides a strategic basis for engineering stress-tolerant yeast strains for efficient fermentation in inhibitor-rich cellulosic hydrolysates. Full article

Traditional fermented beverages from Chiapas, Mexico, represent an important source of microbial diversity, particularly of Saccharomyces cerevisiae. In native strains isolated from traditional fermented beverages, Saccharomyces cerevisiae has been observed to display distinct morphological and physiological traits; therefore, the aim of this study was to evaluate the population growth and the tolerance of twenty isolates to different stress factors such as temperature, osmotic pressure, and high ethanol concentrations, as well as the genetic variability through interdelta analysis, and to determine whether these physiological and molecular characteristics are associated with the type of beverage and the locality of origin. Differences were observed in tolerance to various factors, including high ethanol concentrations and elevated temperatures, as well as in the production of volatile compounds, with Taberna and Mezcal isolates showing notable performance. These isolates were able to withstand temperatures ranging from 43 to 45 °C and ethanol concentrations of up to 17% in Mezcal and Pox isolates, and 15% in Taberna isolates. High concentrations of isoamyl acetate and higher alcohols such as isoamyl alcohol were detected. In addition, the genetic variability of the isolates was evaluated, and its relationship with the type of beverage and the geographical origin of production was explored, including isolates obtained from Taberna, Mezcal, Pox, and Chicha de Chilacayote. Intraspecific variability was assessed through a retrotransposon-based analysis of the interdelta region using different primer combinations (δ1-δ2, δ12-δ21, and δ12-δ2). The generated banding patterns were analyzed using the Unweighted Pair Group Method with Arithmetic Mean (UPGMA), which enabled the identification of molecular variability patterns among the isolates. Furthermore, a UPGMA analysis was performed using physiological and compound production data, revealing a relationship between these characteristics and the geographical origin of the isolates. The results revealed a high degree of intraspecific variability, which was associated with both the type of beverage and the locality of origin of the isolates. Full article

Ethyl butyrate is a typical flavor ester with pineapple-banana scents, but the poor yield from natural fruits limits its feasibility in food and fragrance industries. In this study, dendritic fibrous nano-silica (DFNS) was hydrophobically modified with octyl groups (DFNS-C₈) to immobilize Candida antarctica lipase B (CALB) for solvent-free esterification of ethyl butyrate. The immobilized lipase CALB@DFNS-C₈, with the enzyme loading of 354.6 mg/g and the enzyme activity of 0.064 U/mg protein, achieved 96.0% ethyl butyrate conversion under the optimum reaction conditions where the molar ratio of butyric acid to ethanol was 1:3, with a reaction temperature and time of 40 °C and 4 h. Under the solvent-free catalytic reactions, CALB@DFNS-C₈ presented the maximum catalytic efficiency of 35.1 mmol/g/h and retained 89% initial activity after ten reuse cycles. In addition, the immobilized lipase can efficiently catalyze the synthesis of various flavor esters (such as butyl acetate, hexyl acetate, butyl butyrate, etc.) and exhibits excellent thermostability and solvent tolerance. A molecular docking simulation reveals that the hydrophobic cavity around the catalytic triad stabilizes the acyl intermediate and ensures the precise orientation of both acid and alcohol substrates. This work provides new insights into the sustainable production of flavor esters using highly active and recyclable immobilized lipases through rational carrier hydrophobization and structural confinement design. Full article

Lactic acid is an important biobased chemical widely used in the production of biodegradable plastics, food, and pharmaceuticals. However, the application of flocculant Saccharomyces cerevisiae remains limited in addressing stresses such as high-glucose and inhibitor-rich conditions derived from biomass, particularly in D-lactic acid (D-LA) production. This study investigates two genetically engineered S. cerevisiae F118 strains, ΔCYB2::LpDLDH and ΔPDC1::LpDLDH, for D-LA production under high-glucose and inhibitor-stress conditions that mimic lignocellulosic hydrolysates in shake-flask fermentation. At 150 g/L glucose, ΔCYB2::LpDLDH produced 41 ± 0.73 g/L D-LA, whereas ΔPDC1::LpDLDH yielded 80 ± 1.78 g/L, corresponding to 27% and 53% of the theoretical yield, respectively. Calcium carbonate (CaCO₃) supplementation enhanced glucose consumption and strengthened flocculation in ΔPDC1::LpDLDH. The addition of 5% inhibitory chemical compounds (ICCs) consisting of furfural, HMF, and weak acids redirected carbon flux in ΔCYB2::LpDLDH toward D-LA formation and reduced ethanol byproduct accumulation. Transcriptomic analysis revealed the upregulation of stress-response genes (HOG1, TPS1) and cell-wall remodeling genes (CRH1, SCW10) in response to high-glucose stress. The strongly flocculent F118ΔCYB2::LpDLDH strain exhibited greater tolerance to weak acids and furfural than the weakly flocculent F118ΔPDC1::LpDLDH strain. Metabolomic profiling indicated that under inhibitor stress, carbon flux was diverted from the TCA cycle toward lactate synthesis to maintain redox balance. These findings highlight the multifaceted benefits of flocculation in enhancing strain robustness and D-LA productivity under harsh fermentation environments, providing insights for developing resilient yeast platforms for lignocellulosic bioprocessing. Full article

Calotropis procera, a drought-tolerant shrub widely used in folk medicine, was evaluated for its antimicrobial potential and safety using an integrative in vitro/in silico workflow. Ethanolic leaf extract (EE-CP) displayed a dose-dependent inhibition of Staphylococcus aureus ATCC 2913 and Escherichia coli ATCC 35218, reaching 93% and 52% of the amoxicillin control, respectively (MIC 207 µg mL⁻¹ and 149 µg mL⁻¹). GC-MS and LC-HRMS profiling revealed cardenolides (strophanthidin, gitoxigenin) and indole derivatives as major constituents. Pharmacophore mapping highlighted the essential glycosyltransferase MurG as a likely bacterial target; molecular docking showed that strophanthidin and NCGC00384918 bind MurG more strongly than the native substrate UDP-GlcNAc (ΔG ≤ −9.4 kcal mol⁻¹), a result corroborated by 100 ns molecular dynamics simulations and MM-PBSA binding energies (−96.4 and −49.3 kcal mol⁻¹). EE-CP caused <10% hemolysis up to 1.5 mg mL⁻¹ and exhibited LC₅₀ values of 302 µg mL⁻¹ (human lymphocytes) and 247 µg mL⁻¹ (BHK-21 cells), indicating a narrow but exploitable therapeutic window. Collectively, these findings constitute the first report on Colombian C. procera demonstrating potent anti-Staphylococcus activity, MurG-targeted cardenolides, and acceptable erythrocyte compatibility. This study supports EE-CP as a promising source of lead molecules and antibiotic adjuvants, warranting guided fractionation and in vivo validation to optimize efficacy and mitigate cytotoxicity. Full article

The global sparkling wine market continues to grow steadily, reaching approximately 24 million hectoliters in 2023, with an annual increase of around 4% despite a general decline in overall alcoholic beverage consumption. This growth highlights the importance of employing diverse yeast strains to improve product variety and quality. Flor yeasts are specialized strains of Saccharomyces cerevisiae that develop a biofilm on the surface of certain wines during biological ageing. They possess unique physiological properties, including high ethanol tolerance and the capacity to adhere, which supports wine clarification. They also have the ability to contribute unique volatile compounds and aroma profiles, making them promising candidates for sparkling wine production. This study evaluated two flor yeast strains (G1 and N62), which were isolated from the Pérez Barquero winery during the second fermentation process using the traditional method. Sparkling wines were produced by inoculating base wine (BW) with each strain, and the wines were monitored at 3 bar CO₂ pressure and after 9 months of ageing on lees. Comprehensive metabolomic analysis was performed using GC-MS for volatile compounds and HPLC for nitrogen compounds, with statistical analysis including PCA, ANOVA, Fisher’s LSD, and correction FDR tests. Strain N62 demonstrated faster fermentation kinetics and higher cellular concentration, reaching 3 bar pressure in 27 days compared to 52 days for strain G1. Both strains achieved similar final pressures, 5.1–5.4 bars. Metabolomic profiling revealed significant differences in the profiles of volatile and nitrogen compounds between the two strains. G1 produced higher concentrations of 3-methyl-1-butanol, 2-methyl-1-butanol, and acetaldehyde, while N62 generated elevated levels of glycerol, ethyl esters, and amino acids, including glutamic acid, aspartic acid, and alanine. These findings demonstrate that both flor yeast strains successfully complete sparkling wine fermentation while producing distinct metabolic signatures that could contribute to unique sensory characteristics. This supports their potential as alternatives to conventional sparkling wine yeasts for enhanced product diversification. Full article

Submergence during germination (SG) is a major constraint during sowing, severely limiting the promotion and application of direct-seeded rice. Recent studies have revealed the adaptive mechanisms by which rice responds to SG. At the physiological level, flood-tolerant varieties effectively maintain energy supply and cellular homeostasis by enhancing amylase activity, improving glycolysis and ethanolic fermentation efficiency, promoting embryo sheath elongation, and activating antioxidant enzyme systems; at the molecular level, multiple key genes and signalling pathways have been identified, including SUB1A, OsTPP7, OsGF14h, etc., participating in hypoxia perception, metabolic reprogramming, and hormone signal integration to regulate SG under flooding. In addition, the interactions among plant hormones, such as ethylene, gibberellin, abscisic acid, and cytokinin, also play key roles in the SG process. Future research should prioritize breeding strategies that pyramid multiple genes by integrating gene editing, whole-genome selection, and high-throughput phenotyping to improve seed germination under flood stress. Full article

The ethanol oxidation reaction (EOR) is a key process for direct ethanol fuel cells (DEFCs), offering a high-energy-density and carbon-neutral pathway for sustainable energy conversion. However, the practical implementation of DEFCs is significantly hindered by the EOR due to its sluggish kinetics, complex multi-electron transfer pathways, and severe catalyst poisoning by carbonaceous intermediates. This review provides a comprehensive and mechanistically grounded overview of recent advances in EOR electrocatalysts, with a particular emphasis on the structure–activity relationships of noble metals (Pt, Pd, Rh, Au) and non-noble metals. The effects of catalyst composition, surface structure, and electronic configuration on C–C bond cleavage efficiency, product selectivity (C1 vs. C2), and CO tolerance are critically evaluated. Special attention is given to the mechanistic distinctions among different metal systems, highlighting how these factors influence reaction pathways and catalytic behavior. Key performance-enhancing strategies—including alloying, nanostructuring, surface defect engineering, and support interactions—are systematically discussed, with mechanistic insights supported by in situ characterization and theoretical modeling. Finally, this review identifies major challenges and emerging opportunities, outlining rational design principles for next-generation EOR catalysts that integrate high activity, durability, and scalability for real-world DEFC applications. Full article

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

Catalytic transfer hydrogenation (CTH) and microwave-assisted organic synthesis (MAOS) have each advanced the sustainability of reduction chemistry; however, their combined application to conjugated enones remains largely unexplored. To the best of our knowledge, no unified protocol has been reported for the rapid, one-pot conversion of chalcones into saturated alcohols under microwave irradiation. Herein, we report a concise and green method that integrates MAOS with Pd/C-catalyzed CTH, employing inexpensive ammonium formate in ethanol. In contrast to state-of-the-art hydrogenations that require pressurized H₂ or costly metal complexes, our strategy (i) achieves complete conversion within 20 min at 60 °C, (ii) tolerates both electron-rich and electron-poor substrates, (iii) reduces nitro-substituted chalcones in a single step, and (iv) consumes < 0.005 kWh per reaction—an approximately 250-fold energy saving relative to conventional procedures. These results position microwave-driven CTH as a scalable alternative for synthesizing pharmacologically relevant saturated alcohol scaffolds from readily available chalcones. Full article

The NAD⁺-dependent alcohol dehydrogenase AdhB from Aromatoleum aromaticum EbN1 belongs to family III of Fe-dependent alcohol dehydrogenases. It was recombinantly produced in Escherichia coli and biochemically characterized, showing activity only with ethanol or n-propanol. The enzyme contained substoichiometric amounts of Fe, Zn, and Ni and a yet unidentified nucleotide-like cofactor, as indicated by mass spectrometric data. As suggested by its narrow substrate spectrum and complementation of a related species to growth on ethanol, the most probable physiological function of AdhB is the oxidation of short aliphatic alcohols such as ethanol or n-propanol. The enzyme also exhibits a very high tolerance to ethanol and n-propanol, showing moderately substrate-inhibited Michaelis–Menten kinetics up to concentrations of 20% (v/v). AdhB can also be applied biotechnologically to convert acetate to ethanol in coupled enzyme assays with the tungsten enzyme aldehyde oxidoreductase, showing activity with either another aldehyde or pre-reduced benzyl viologen as electron donors. Full article

Honey possesses unique properties, characterized by its high sugar concentration and the synergistic interaction among nectar, pollen, bees, and yeasts. These features render it an exceptional substrate for exploring microbial diversity for bioprospecting purposes. In this study, we characterized fermentative yeast populations from 19 honey samples collected in Northern Patagonia, Argentina. A total of 380 yeast isolates were obtained, identifying eight yeast species. Starmerella magnoliae emerged as the dominant species, found in 76% of samples and representing 63% of total isolates. Intraspecific diversity analysis, using mtDNA-RFLP and sequencing of nuclear genes (FSY1 and FFZ1), revealed the presence of two distinct phylogeographic populations. Phenotypic assays indicated that most S. magnoliae strains tolerate high sulfite and ethanol concentrations, alongside exhibiting broad temperature tolerance, with some strains thriving even at 37 °C. Despite the fact that none of the strains completed the fermentation, microfermentation trials confirmed the fructophilic nature of this species and highlighted intraspecific variability in glycerol and acetic acid production. These findings underscore S. magnoliae as a promising non-Saccharomyces yeast for the fermented beverage industry. Full article

Phthalic acid esters (PAEs), ubiquitously employed as a plasticizer, have been classified as priority environmental pollutants because of their persistence, bioaccumulation, and endocrine-disrupting properties. As a characterized PAE-degrading strain of marine origin, Mycolicibacterium phocaicum RL-HY01 utilizes di-(2-ethylhexyl) phthalate (DEHP) as its sole carbon and energy source. Genome sequencing and RT-qPCR analysis revealed a previously uncharacterized hydrolase gene (dehpH) in strain RL-HY01, which catalyzes ester bond cleavage in PAEs. Subsequently, recombinant expression of the cloned dehpH gene from strain RL-HY01 was established in Escherichia coli BL21(DE3). The purified recombinant DehpH exhibited optimal activity at 30 °C and pH 8.0. Its activity was enhanced by Co²⁺ and tolerant to most metal ions but strongly inhibited by EDTA, SDS, and PMSF. Organic solvents (Tween-80, Triton X-100, methanol, ethanol, isopropanol, acetone, acetonitrile, ethyl acetate, and n-hexane) showed minimal impact. Substrate specificity assay indicated that DehpH could efficiently degrade the short and long side-chain PAEs but failed to hydrolyze the cyclic side-chain PAE (DCHP). The kinetics parameters for the hydrolysis of DEHP were determined under the optimized conditions, and DehpH had a V_max of 0.047 ± 0.002 μmol/L/min, K_m of 462 ± 50 μmol/L, and k_cat of 3.07 s⁻¹. Computational prediction through structural modeling and docking identified the active site, with mutagenesis studies confirming Ser228, Asp324, and His354 as functionally indispensable residues forming the catalytic triad. The identification and characterization of DehpH provided novel insights into the mechanism of DEHP biodegradation and might promote the application of the target enzyme. Full article

Potentially probiotic yeasts isolated from foodstuffs can be used as components in functional fermented beverages. To date, there have been no reports on the use of Saccharomyces cerevisiae var. boulardii, Pichia kudriavzevii, Metschnikowia pulcherrima, or Hanseniaspora uvarum isolates in the production of a traditional Polish beverage called underbeer (podpiwek). The aim of the study was to determine the usefulness of six isolates of the above-mentioned species as starter cultures for the fermentation of underbeer. First, the important characteristics of the yeasts, like ethanol tolerance and H₂S production, were examined. In the next stage, the wort was fermented by the tested yeasts, and cell viability, fermentation vigor, sugar assimilation, and production of metabolites, as well as properties of the beverage (pH, titratable acidity, color, and turbidity), were determined. Saccharomyces yeasts tolerated the addition of ethanol up to 16% (v/v), while Pichia, Metschnikowia, and Hanseniaspora tolerated up to 10% (v/v) ethanol, and all except H. uvarum produced H₂S. The yeasts remained viable in the beverages for 1 month at the required level, utilized glucose, fructose and partially complex carbohydrates, and produced ethanol (S. cerevisiae, P. kudriavzevii, and M. pulcherrima) and organic acids such as tartaric, malic, and citric acid. The underbeers became sour and showed varying turbidity and a color corresponding to pale-amber beers. All tested strains produced fermented beverages that were low- or non-alcoholic with different properties. This experiment may be a starting point for research into regional products as probiotic or synbiotic foods; however, further research is required for selection of the best strains for underbeer fermentation. Full article