Search Results (3,607)

Pulque is a traditional Mexican beverage produced through the fermentation of agave sap (aguamiel). Its primary sensory properties are attributed to the fermentative activity of Saccharomyces cerevisiae, Leuconostoc mesenteroides, and Zymomonas mobilis. However, the overproliferation of these microorganisms results in an extremely short shelf life, which hinders its commercialization. Tomatillo accrescent calyx extract (TACE) shows potential as a food preservative due to its high physalin content. Therefore, this study aimed to evaluate the effect of adding microencapsulated TACE on the shelf life and organoleptic properties of pulque. The extract demonstrated effective antimicrobial activity against L. mesenteroides, Z. mobilis, and S. cerevisiae, successfully delaying further fermentation. Additionally, the addition of TACE prevented an excessive increase in acidity, maintaining values suitable for consumption for up to 15 days, in accordance with regulatory standards, while the viscosity and alcohol content were not negatively affected. These findings suggest that TACE has significant potential for preserving both the microbiological and sensory quality of pulque. Full article

Oxidative stress is one of the major environmental stresses that the fungal pathogen Candida albicans frequently encounters. In view of the negative regulatory effect of Ume6 on autophagy in Saccharomyces cerevisiae and the close link between autophagy and oxidative stress in mammals, we explored the regulatory effect of Ume6 on autophagy and oxidative stress in C. albicans in this study. Here, we identify the transcriptional regulator Ume6 as a key positive regulator of autophagy under oxidative stress conditions. Deletion of UME6 resulted in reduced autophagy levels under H₂O₂ treatment, correlating with reduced transcriptional expression of core autophagy-related genes. Although UME6 deletion alone did not alter H₂O₂ sensitivity, it significantly exacerbated the sensitivity of a catalase mutant, revealing a functional role for Ume6 in oxidative stress tolerance. Intriguingly, we discovered that 3-methyladenine (3-MA), a canonical autophagy inhibitor in other systems, acts as an autophagy activator in C. albicans, promoting Atg8 transport to the vacuole and enhancing autophagy levels. This 3-MA-induced autophagy alleviated oxidative stress damage, as evidenced by improved growth and protection of vacuolar membrane integrity in H₂O₂-treated cells. Furthermore, deletion of UME6 or nitrogen starvation reduced apoptosis under oxidative stress, including decreased Annexin-V binding, metacaspase activation, mitochondrial membrane depolarization, and mitochondrial cytochrome c release. This study uncovers the critical role of Ume6 in governing oxidative stress, autophagy, and apoptosis. Full article

γ-Aminobutyric acid (GABA), a major inhibitory neurotransmitter, is known for its physiological functions in alleviating anxiety and improving sleep. Currently, high-yielding GABA food products are mainly obtained through screening wild-type high-producing strains (e.g., Saccharomyces cerevisiae isolated from Sichuan pickles yielding 0.67 g/L) or employing co-culture systems (e.g., Enterococcus faecium and Lactiplantibacillus plantarum reaching 6.35 g/L). While effective, these methods often rely on natural screening strains or multi-microbial interactions. This study employed CRISPR-Cas9 technology to knockout the UGA1 gene in Saccharomyces cerevisiae, a key gene responsible for GABA degradation. Starting from the low higher alcohol Saccharomyces cerevisiae SY-LH, we successfully constructed the recombinant strain SY-LHU. Remarkably, this study discovered a significant upregulation of GAD1 gene expression following UGA1 knockout, which further enhanced GABA synthesis capacity. Under optimal fermentation conditions (inoculum size 4 × 10⁷ cells/mL, wort concentration 10 °P, sugar addition 60 g/L, 30 °C for 10 days, and mixing the malt broth every 48 h), the validation fermentation was performed and the GABA content in the wort beverage reached 280.36 mg/L, representing a 385.4% increase compared to the pre-optimization level. Furthermore, sensory evaluation by a trained panel yielded a mean score of 88, with no significant off-flavors detected, demonstrating the product’s high consumer acceptance. This pioneering work provides a novel and feasible technical pathway for developing functional alcoholic beverages with sleep-aiding properties. Full article

Fuqu plays a crucial role in initiating fermentation and flavor compound production during sesame flavor-type baijiu fermentation. However, selecting microorganisms for Fuqu to enhance flavor compound production remains a challenge. This work designs a synthetic microbial community (SynCom) for Fuqu to improve the production of flavor compounds, with a focus on the diversity of flavor compounds and the content of a key flavor compound—sulfur compounds. Through multi-omics analysis, 13 genera (Aspergillus, Bacillus, Lactobacillus, Leuconostoc, Pediococcus, Pichia, Saccharomyces, Trichosporon, Weissella, Candida, Torulaspora, Clavispora, and Wickerhamomyces) were identified as core microbiota involved in the production of those flavor compounds, and these core microbiota were used to construct a SynCom to enhance flavor compound production in baijiu fermentation. The resulting SynCom exhibited the highest flavor compound diversity (0.64) and 3-(methylthio)-1-propanal content (618.14 μg/kg) in simulative fermentation. In large-scale production, Fuqu made with the SynCom achieved greater flavor compound diversity (0.56) and a higher concentration of 3-(methylthio)-1-propanal (590 μg/kg) compared to commercial Fuqu (0.40 and 324 μg/kg, respectively) (p < 0.05). The results demonstrated that the SynCom developed for Fuqu effectively enhances the production of flavor compounds. This work provides a strategy for constructing SynCom to improve the formation of flavor compounds in baijiu fermentation. Full article

Plasmopara viticola (Pv), the causal agent of downy mildew, is one of the most damaging pathogens affecting grapevine. Current control strategies largely depend on copper-based fungicides and synthetic chemicals, raising increasing concerns related to environmental sustainability and pathogen resistance. This study evaluated the efficacy of a novel Saccharomyces cerevisiae extract (U) as an inducer of resistance in the grapevine–Pv interaction. Microscopic observations revealed the ability of U to inhibit Pv spread over the leaf. Additionally, biochemical and molecular responses were analyzed in grapevine leaves subjected to four treatments: plants treated only with water (U⁻/Pv⁻; i.e., control) or U (U⁺/Pv⁻), inoculated with Pv (U⁻/Pv⁺), or both treated with U and then inoculated with Pv (U⁺/Pv⁺). Fully expanded leaves were sampled at 2-, 5-, 24-, and 72-h post inoculation (hpi). In U⁺/Pv⁻ leaves, jasmonic, salicylic and abscisic acid (JA, SA, and ABA), as well as hydrogen peroxide (H₂O₂) increased at 2 hpi (+44, +33, +38%, and 3-fold, respectively), accompanied by upregulation of pr1 (2-fold higher than control, respectively), suggesting the capacity of U to trigger the plant alert system. In U⁻/Pv⁺ leaves, peaks of JA and H₂O₂ occurred at 24 hpi (+40% and 4-fold higher than control), followed by marked ethylene emissions and upregulation of pr1 and pr2 (i.e., genes associated with Pv defense; around 2-fold, averagely) at 72 hpi, confirming the progression of infection. In contrast, U⁺/Pv⁺ leaves showed stronger peaks of H₂O₂ at both 2 and 5 hpi (7-fold and +58%, respectively), together with SA accumulation and upregulation of pr1, pr2, eds1, and chit1b at 72 hpi (more than 2-fold), suggesting a priming effect of U. Overall, U effectively enhanced grapevine defense responses and limited Pv development, highlighting its potential as a sustainable disease management strategy. Full article

Rose hip processing generates seed-rich by-products that remain underexplored beyond oil extraction, despite their potential as a source of phenolic compounds and antioxidant activity. This study investigates the effect of bioprocessing (short-term fermentation) on the phenolic composition and antioxidant activity of rose hip (Rosa spp.) seed by-products, with relevance to cosmetic-oriented applications related to oxidative stress modulation. Rose hip seeds were obtained after juice production and subjected to short-term fermentation (14 days at 21 °C) using Saccharomyces cerevisiae, followed by mechanical separation and drying. Non-fermented and bioprocessed seeds were analyzed for individual phenolic compounds and antioxidant activity (DPPH, ABTS, FRAP), and correlation and multivariate analyses were conducted. Bioprocessing reduced total identified phenolics from 15.79 to 10.72 mg/g DW (≈32%), primarily due to a decrease in epigallocatechin (10.89 to 6.50 mg/g DW). In parallel, the relative contribution of phenolic acids increased, including gallic acid (0.50 to 0.60 mg/g DW) and salicylic acid (0.98 to 1.20 mg/g DW), indicating a selective compositional redistribution accompanied by partial degradation. Antioxidant activity decreased after bioprocessing (DPPH ~340 to ~250 µmol TE/g DW) but remained substantial. Correlation analysis identified epigallocatechin as the main contributor to antioxidant capacity. These findings show that rose hip seeds behave as a process-sensitive phenolic matrix in which bioprocessing alters the balance of individual compounds without complete loss of antioxidant activity. The results indicate that seed-derived by-products retain functional potential for further valorization in cosmetic-oriented applications. Full article

The transition towards a circular bioeconomy is essential to mitigate the environmental pressures caused by the increasing global demand for food and energy. Agro-food waste (AFW) is a plentiful, inexpensive feedstock, exploitable in biorefineries to produce valuable molecules. The aim of this study was to isolate native non-conventional yeasts (NCY) from various AFW and to evaluate their potential for the ‘natural’ synthesis of aroma compounds via fermentation. Ten strains were isolated and identified as belonging to Saccharomyces cerevisiae, Pichia kluyveri, Pichia californica and Wickerhamomyces anomalus species. The fermentative performance and production of aroma volatile compounds were tested using different household wastes as substrates. Figs containing substrate, which is the richest in fermentable sugars, allowed for the fastest microbial adaptation and highest yields of volatile compounds. HS-SPME-GC/MS analysis revealed that the most prominent compounds were isoamyl alcohol, ethyl acetate and isoamyl acetate with the highest production levels showed by W. anomalus YDSCYP4 and P. kluyveri YDSCYP5. Enzymatic profiling revealed significant arylamidase and esterase activities in the selected strains, related to their role in the hydrolysis of aroma precursors. These findings demonstrate the efficiency of these autochthonous yeasts for the sustainable production of aroma compounds, supporting the development of eco-friendly biotechnological processes. Full article

Deoxynivalenol (DON), a Group III carcinogenic mycotoxin frequently detected in cereals and animal-derived food products, poses serious health risks to animals and humans. In this study, we developed a genetically engineered Saccharomyces cerevisiae strain as a proof-of-concept platform for DON detoxification. The yeast was engineered to co-express two detoxification genes, YTDepA and YTDepB (homologs of DepA and DepB from Devosia mutans 17-2-E-8) originally identified in Youhaiella tibetensis. Concurrently, the pyrroloquinoline quinone (PQQ) biosynthesis gene cluster from Klebsiella pneumoniae was integrated to supply the essential cofactor. Gene expression was verified by qRT-PCR and Western blot. The recombinant strain demonstrated a significant 13.98% detoxification of DON after 72 h of fermentation (p < 0.05), as confirmed by HPLC–MS, while the strain expressing only the PQQ cluster showed no detoxification activity. This study establishes an integrated yeast cell factory for DON detoxification and highlights key limitations to guide future optimization efforts. Full article

Copper is a crucial cofactor that sustains multiple cellular electron-transfer reactions, making it an essential element for life. However, cytotoxic levels of copper can cause structural damage and cell death through the production of reactive oxygen species (ROS) and nonspecific attacks on proteins. Moreover, immune cells, including neutrophils and macrophages, accumulate copper to induce oxidative bursts that kill engulfed pathogens. Therefore, a well-regulated copper homeostasis system is required for the human commensal fungus Candida albicans to thrive in extreme host environments. Remarkably, C. albicans exhibits higher copper tolerance than the nonpathogenic model yeast Saccharomyces cerevisiae, suggesting the presence of a specific copper tolerance mechanism that supports its adaptability to copper stress. Ndt80 is a versatile transcription factor that regulates several biological processes in C. albicans, ranging from morphological control to drug resistance. This study further reveals that Ndt80 may contribute to copper tolerance by regulating copper transporters and copper-dependent superoxide dismutases (Sods). Additionally, RNA sequencing and complementary approaches uncovered the involvement of Ndt80 in plasma membrane integrity and mitochondrial respiration under copper stress, further linking Ndt80 to copper tolerance. Together, these results broaden our understanding of Ndt80 functions and provide new insights into copper tolerance in C. albicans. Full article

Lycium barbarum–Polygonatum cyrtonema composite jiaosu (LBPCJ) was prepared by sequential dual-species fermentation and evaluated in a mouse model of alcohol-induced liver injury. Following process optimization, a yeast-first sequential strategy with intermediate pasteurization was selected, comprising an initial Saccharomyces cerevisiae fermentation step, intermediate pasteurization, and a subsequent Lactiplantibacillus plantarum fermentation step. Fermentation reduced pH from 4.68 to 3.51 and increased total acidity from 61.06 to 135.39 g LA/L and total phenolic content from 3.01 to 9.39 mg GAE/mL. In vitro antioxidant-related activities were also higher after fermentation, with DPPH, ABTS, and •OH scavenging rates increasing by 39.90%, 29.78%, and 11.10%, respectively. In mice, LBPCJ administration was associated with lower liver index and serum aminotransferase levels, together with attenuated hepatic histopathological alterations, with the high-dose group (15 mL/kg BW) showing the clearest response. These changes were accompanied by higher hepatic SOD and GSH levels and lower MDA, TNF-α, IL-1β, and IL-6 levels. LBJ and PCJ also improved several measured indicators, while LBPCJ showed changes across multiple endpoints under the tested conditions. Overall, sequential fermentation markedly altered the physicochemical and antioxidant-related properties of LBPCJ, and LBPCJ administration improved multiple indicators related to alcohol-induced liver injury in mice, although the specific constituents and underlying mechanisms remain to be clarified. Full article

Consumer interest in low-SO₂ white wines is increasing; however, such approaches may reduce compositional and sensory predictability. This study evaluates how three fermentation strategies—SO₂ addition and Saccharomyces cerevisiae ES181 inoculation (SO₂Sc), spontaneous fermentation (NoSO₂-Spont), and inoculation with S. cerevisiae ES181 without SO₂ addition (NoSO₂Sc)—shape the chemical profile, polyphenolic composition, colour, microbiological status, and sensory perception of ‘Solaris’ wines relative to the must (reference). A single batch of ‘Solaris’ must (one press run) was split into three variants and fermented under identical temperature conditions (12 ± 0.5 °C), followed by cool ageing and natural sedimentation prior to bottling. Basic oenological parameters, selected fermentation by-products, viable yeast counts, CIE Lab colour, targeted polyphenolics (phenolic acids, flavonols, flavan-3-ols, and stilbenes), PCA of by-products, and blind sensory evaluation were assessed. The NoSO₂-Spont variant showed reduced fermentation completeness (higher residual sugars and lower ethanol) and the highest volatile acidity, together with elevated glycerol and several higher alcohols, and received the lowest sensory ratings. The SO₂Sc variant yielded the most controlled outcome, with the lowest volatile acidity, the brightest colour (higher L*, lower b*), and the highest sensory acceptance. The NoSO₂Sc variant produced intermediate sensory scores and a higher total phenolic content; however, volatile acidity remained high and viable yeast counts were the greatest, indicating increased susceptibility to microbiological activity during extended pre-bottling handling. Overall, the SO₂Sc strategy provides the greatest chemical stability and sensory acceptance, whereas low-SO₂ regimes require a hurdle approach (oxygen control, residual sugar management, hygiene, and stabilisation) to limit spoilage development and post-bottling refermentation. Full article

Weaning impairs intestinal function and growth performance in piglets. This study evaluated a fermented herbal formulation (FHF) composed of five bioactive herbal ingredients—Radix isatidis, Folium isatidis, Radix scutellariae, Fructus forsythiae, and Radix glycyrrhizae—fermented with Enterococcus faecium and Saccharomyces cerevisiae and characterized by flavonoids, phenolic acids, and hydroxylated fatty acids, using the porcine intestinal epithelial cell line (IPEC-J2) and weaned piglets. In vitro, IPEC-J2 cells were pretreated with FHF extract (100–1000 μg/mL) for 3 h prior to lipopolysaccharide (LPS) challenge. In vivo, 72 piglets were weaned at 32 days of age and, after a 3-day post-weaning adaptation period, entered a 35-day feeding trial. The piglets were then randomly assigned to three treatment groups: control (basal diet), A1 (basal diet + 0.4% FHF), and A2 (basal diet + 0.6% FHF during days 1–18, followed by 0.3% FHF during days 19–35). FHF dose-dependently alleviated the LPS-induced decrease in cell viability and suppressed IL-6, IL-8, IL-1β, and TNF-α expression. In piglets, the A2 group showed higher final body weight, average daily gain (ADG), and average daily feed intake (ADFI), lower feed conversion ratio (FCR), and a lower diarrhea rate than the control group. FHF also improved intestinal morphology, reduced serum TNF-α and diamine oxidase (DAO) levels, increased jejunal tight junction protein expression, enriched Limosilactobacillus and Lactobacillus, and elevated acetic and butyric acids. FHF improved intestinal health and growth performance in weaned piglets, with the A2 group showing the best overall efficacy. Full article

Polyamines, putrescine, spermidine and spermine, are essential polycationic metabolites present in all eukaryotic cells, where they regulate fundamental processes including nucleic acid stabilization, translation, and stress responses. Spermidine synthase (SPDS), a member of the aminopropyltransferase (APT) family, catalyzes the transfer of an aminopropyl group from decarboxylated S-adenosylmethionine (dc-SAM) to putrescine to form spermidine. Although genomic analyses predict the presence of SPDS homologs in multiple fungal species, polyamine biosynthesis has not been experimentally characterized in the multidrug-resistant fungal pathogen Candidozyma auris. Here, we report the biochemical and functional characterization of the C. auris spermidine synthase, CauSpe3. The CauSPE3 gene complemented a Saccharomyces cerevisiae spe3Δ mutant demonstrating conserved function in vivo. Recombinant CauSpe3 was expressed in Escherichia coli, purified and analyzed using the fluorescence-based DAB-APT assay, which uses 1,2-diacetylbenzene (DAB) for polyamine detection. CauSpe3 catalyzed efficient conversion of putrescine to spermidine in the presence of dc-SAM, with K_half values of 65.5 ± 7.11 µM for putrescine and 66.9 ± 2.09 µM for dc-SAM, and V_max values of 7.1 ± 0.57 and 7.9 ± 0.12 nmol·µg⁻¹·min⁻¹, respectively. A catalytic-site mutant and heat-inactivated enzyme showed no detectable activity, and product formation was confirmed by means of thin-layer chromatography and mass spectrometry. These findings establish CauSpe3 as a functional spermidine synthase. Full article

The gut microbiome plays a central role in human health, and probiotics are widely used to support microbial balance, though their efficacy depends on multiple factors. This study assessed the potential of commercial probiotics Saccharomyces cerevisiae var. boulardii, Weizmannia coagulans and Lacticaseibacillus rhamnosus by evaluating in vitro gastrointestinal kinetics, pharmaceutical stability, and antioxidant effects in chamomile tea. Growth across a broad pH range was modeled kinetically, while survival and inactivation were quantified in simulated gastric and intestinal fluids. Antibiotic and antifungal susceptibility was determined using disk diffusion, and antioxidant activity of fortified chamomile tea was assessed via DPPH radical scavenging. Results revealed distinct strain-dependent responses. S. cerevisiae var. boulardii and W. coagulans showed the highest gastrointestinal tolerance. The increase in fluid volume reduced survival during the gastric phase but improved survival in the intestinal phase, reflecting different stress responses. Antimicrobial susceptibility also varied, with S. cerevisiae var. boulardii exhibiting the highest resistance. Probiotic fortification enhanced chamomile tea’s antioxidant capacity, particularly for S. cerevisiae var. boulardii and L. rhamnosus. These findings provide quantitative insight into strain- and volume-dependent gastrointestinal performance, guiding the optimization of capsule formulations and the development of clean-label products combining probiotic and antioxidant benefits. Full article

During alcoholic fermentations, some non-Saccharomyces yeasts are often displaced by Saccharomyces cerevisiae. It remains unclear whether this displacement is mediated by metabolites produced by S. cerevisiae or depends on cell–cell contact. This study evaluated the effects of extracellular metabolites produced by S. cerevisiae on the growth and fermentative performance of Kluyveromyces marxianus isolated from mezcal fermentations. The development of both yeasts was evaluated in monocultures and in co-cultures with physical contact. Indirect interaction was also tested by exchanging cell-free fermented media. The growth and fermentative response of K. marxianus in cell-free S. cerevisiae-fermented medium showed modulation that depended on the growth phase during which the exchange was performed. The exchange performed at 6 h (exponential phase) limited the maximum growth of K. marxianus and resulted in lower fermentative performance. When the exchange was done during the stationary phase (17.5 h), K. marxianus exhibited a longer stationary phase and better fermentative performance. Finally, when the exchange was performed at 24 h (the beginning of the death phase), the effects on survival and fermentative performance were less pronounced. Furthermore, co-culture with cell–cell contact showed that direct competition and/or mechanisms dependent on physical contact intensify the displacement of K. marxianus. The results show that direct cell–cell contact promotes greater inhibition of K. marxianus by S. cerevisiae, which is relevant for the design of mixed fermentations aimed at achieving a greater contribution of non-Saccharomyces yeasts to the organoleptic characteristics of alcoholic beverages. Full article