Search Results (300)

In response to the growing interest in less conventional alcoholic beverages, this study aimed to identify novel yeast strains suitable for sake production, with a focus on their potential application in bioflavouring. Commercially available strains of bottom-fermenting brewing yeasts (Saccharomyces pastorianus), a cryotolerant wine yeast (Saccharomyces bayanus), and a wild wine yeast (Torulaspora delbrueckii) were evaluated. The quality characteristics of sake obtained using non-conventional yeasts were compared with sake produced using Saccharomyces cerevisiae K7, one of the most commonly used strains in sake brewing. Sake made with non-conventional yeasts exhibited differences in fermentation kinetics, chemical composition, and sensory properties. Wine yeasts produced sake with the most favorable ester profile, markedly distinct from those obtained with other yeast strains used in the study. Compared to the conventional strain, the concentrations of the key contributors to the fruity/floral aroma, namely 3-methylbutyl acetate and ethyl hexanoate, in sake produced with S. bayanus were higher by 249.5% and 199.3%, respectively. The wine yeast S. bayanus may be considered the most promising strain for sake production due to its ability to generate elevated levels of volatile aroma compounds associated with Ginjo-ka characteristics, as well as its effectiveness in supporting a consistent and efficient alcoholic fermentation process. Full article

This review explores the accumulated research and technological potential of Saccharomyces eubayanus, a cold-tolerant wild yeast first isolated in 1997 from the Andean-Patagonian forests of Argentina but formally described in 2011. S. eubayanus has garnered attention since it was identified as the missing parent of the lager-beer yeast S. pastorianus and because it demonstrated valuable fermentative skills and an unexpected large intraspecific genetic diversity. The article recapitulates the characterization of the fermentative capacity of the type strain, as well as its ability to produce distinctive aromatic profiles compared to conventional lager yeasts. We discuss how these features have driven the development of improved strains through experimental evolution and the generation of interspecific hybrids with S. cerevisiae exhibiting appropriate fermentation performance and a broad aromatic diversity. We also aim to address the applications of S. eubayanus in commercial brewing, especially in the craft beer industry, and highlight its potential to add value and/or regional identity to beer through novel flavor profiles. Finally, the review outlines the main challenges limiting large-scale implementation, emphasizing the importance of continued research into strain development and brewing strategies to fully harness the potential of this wild yeast species. Full article

Cissampelos pareira is a medicinal plant with the potential effect of treating diabetes, commonly used by the Dai people in southern Yunnan Province. However, the wild resources of C. pareira are currently scarce. Endophytic fungi are a natural component of medicinal plants, while also serving as important repositories for discovering active natural products. In this study, we focused on 2-year-old C. pareira plants cultivated in potted and non-potted conditions. The community structure of endophytic fungi in the roots, stems, leaves, and flowers of two cultivation methods of C. pareira was investigated by using high-throughput sequencing (HTS) and traditional culture methods. Through HTS, we discover that the richness and diversity of endophytic fungi in C. pareira are associated with its growth environment and plant tissues. The endophytic fungi richness of C. pareira showed significant differences between the two habitats. And significant differences existed in the diversity of root endophytic fungi of C. pareira compared to those in the stems, leaves, and flowers. Additionally, the richness of endophytic fungi in the stems showed significant differences from that in the roots, leaves, and flowers. The results obtained using traditional culture methods revealed 69 endophytic fungi strains, classified into 2 phylum, 4 classes, 11 orders, 23 families, and 69 genera. The fermentation products of the obtained strains were evaluated for in vitro α-glucosidase inhibitory activity, and the results demonstrated that 11 endophytic fungi strains exhibited an inhibition rate exceeding 80%. The above-mentioned study can provide a theoretical basis for a comprehensive understanding of the community composition and diversity of endophytic fungi in C. pareira. Full article

This study provides a comprehensive analysis of the microbial dynamics involved in the fermentation process of traditional Musalais wine, an intangible cultural heritage of Xinjiang. Utilizing metagenomic sequencing, we identified 2894 microbial species, of which 494 persisted throughout the fermentation process. Saccharomyces cerevisiae was the dominant species, with its prevalence increasing from 97.35% in the early phase to 99.38% in the mid phase, before slightly decreasing to 98.79% in the late phase. Additionally, 24 non-Saccharomyces yeast species, including Hanseniaspora uvarum, Lachancea thermotolerans, and Torulaspora delbrueckii, were detected. Common species associated with other fermented foods, including Wickerhamomyces anomalus, Kluyveromyces marxianus, Saccharomyces eubayanus, and Zygosaccharomyces parabailii, were also identified. Notably, species not previously used in food fermentation, such as Saccharomyces jurei, Sodiomyces alkalinus, Vanrija pseudolonga, and Moesziomyces antarcticus, were also identified in this study. Furthermore, the Kyoto Encyclopedia of Genes and Genomes (KO) and Gene Ontology (GO) revealed notable variations in metabolic pathways and enriched functional genes. In addition, a total of 82 volatile compounds were detected in the final product, with higher alcohols (60.12%), esters (37.80%), and organic acids (1.80%) being the most prevalent. These results offer important insights into microbial interactions and their influence on Musalais wine quality, laying the groundwork for optimizing the fermentation process. Full article

Wild ales represent a diverse category of spontaneously fermented beers, influenced by complex microbial populations and variable ingredients. This study employed an integrated metabolomic profiling approach combining proton nuclear magnetic resonance (¹H NMR) spectroscopy, liquid chromatography–mass spectrometry (LC-MS), and spectrophotometric assays (DPPH and FRAP) to characterize the molecular composition and antioxidant potential of 22 wild ales from six countries. A total of 53 compounds were identified and quantified using NMR, while 62 compounds were identified by using LC-MS. The compounds in question included organic acids, amino acids, sugars, alcohols, bitter acids, phenolic compounds, and others. Ingredient-based clustering revealed that the addition of dark fruits resulted in a significant increase in the polyphenolic content and antioxidant activity. Concurrently, herb-infused and light-fruit beers exhibited divergent phytochemical profiles. Prolonged aging (>18 months) has been demonstrated to be associated with increased levels of certain amino acids, fermentation-derived aldehydes, and phenolic degradation products. However, the influence of maturation duration on the antioxidant capacity was found to be less significant than that of the type of fruit. Country-specific metabolite trends were revealed, indicating the influence of regional brewing practices on beer composition. Correlation analysis was employed to identify the major contributors to antioxidant activity, with salicylic, dihydroxybenzoic, and 4-hydroxybenzoic acids being identified as the most significant. These findings underscore the biochemical intricacy of wild ales and exemplify metabolomics’ capacity to correlate compositional variation with functionality and authenticity in spontaneously fermented beverages. Full article

2-Phenylethanol (2-PE), an aromatic alcohol with a rose-like fragrance, is widely used in the food, pharmaceutical, and high-end cosmetic industries. In this study, a high-yield 2-PE-producing strain was isolated and identified as Saccharomyces cerevisiae based on morphological characterization and taxonomic identification. Fermentation medium components (carbon and nitrogen sources) were optimized through single-factor experiments in shaking flasks, and fermentation medium with 40 g/L glucose, 5 g/L malt extract, 1.75 g/L corn steep liquor, 2.5 g/L yeast extract, 5 g/L malt extract, 1.75 g/L corn steep liquor was considered suitable for 2-PE production. RT-qPCR results indicated that corn steep liquor activates expression of genes related to the shikimate pathway and Ehrlich pathway (pha2, aro4, aro8, and aro9), thereby promoting the synthesis of 2-PE through these pathways. Excess yeast extract inhibited the expression of aro8 and aro9, while enhancing the expression of tdh3 and adh2, thus promoting the de novo synthesis of 2-PE. Furthermore, fermentation in a 5 L bioreactor was applied to investigate the effects of feeding strategies, inoculum proportion, and pH on 2-PE production. With a pH of 5.5 and10% inoculum proportion, the supplementation of the substrate L-Phe led to a 2-PE production of 4.81 g/L after 24 h of fermentation. Finally, in situ product recovery (ISPR) techniques was applied to alleviate 2-PE cytotoxicity, achieving a production of 6.41 g/L. This process offers a promising strategy for producing 2-PE efficiently and naturally, paving the way for further industrial applications in food, pharmaceutical, and cosmetic sectors. Full article

Secreted bacteriolytic proteases L1 and L5 of the Gram-negative bacterium Lysobacter capsici XL hydrolyze peptide bridges in bacterial peptidoglycans. Such specificity of action determines the prospects of these enzymes for medicine with the view of creating new antimicrobial drugs to combat antibiotic-resistant strains of pathogens. This research concerns the development of successful expression systems for producing active enzymes L1 and L5 in sufficient amounts for comprehensive studies. Based on L. capsici XL strains with deletions in the alpA (enzyme L1) and alpB (enzyme L5) genes and the constructed expression vectors pBBR1-MCS5 P_T5–alpA and pBBR1-MCS5 P_T5–alpB, we obtained expression strains L. capsici P_T5–alpA and L. capsici P_T5–alpB, respectively. The yields of enzymes L1 and L5 in the developed strains increased by 4 and 137 times, respectively, as compared to the wild-type strain. The cultivation of the expression strains was successfully scaled up under non-selective conditions in a 10-L bioreactor. After fermentation, the yields of enzymes L1 and L5 were 35.48 mg/L and 57.11 mg/L, respectively. The developed homologous expression systems of bacteriolytic proteases L1 and L5 have biotechnological value as compared to those obtained by us earlier based on heterologous expression systems, which have lower yields and labor-intensive purification schemes. Full article

This study investigates the potential of sugar beet pulp (SBP), a lignocellulosic by-product of sugar production, as a low-cost substrate for biohydrogen and biomass generation using Escherichia coli under dark fermentation conditions. Two strains—BW25113 wild-type and a genetically engineered septuple mutant—were employed. SBP was pretreated via thermochemical hydrolysis, and the effects of substrate concentration, dilution, and glycerol supplementation were evaluated. Hydrogen production was highly dependent on substrate dilution and nutrient balance. The septuple mutant achieved the highest H₂ yield in 30 g L⁻¹ SBP hydrolysate (0.75% sulfuric acid) at 5× dilution with glycerol, reaching 12.06 mmol H₂ (g sugar)⁻¹ and 0.28 mmol H₂ (g waste)⁻¹, while the wild type under the same conditions yielded 3.78 mmol H₂ (g sugar)⁻¹ and 0.25 mmol H₂ (g waste)⁻¹. In contrast, undiluted hydrolysates favored biomass accumulation over H₂ production, with the highest biomass yield (0.3 g CDW L⁻¹) obtained using the septuple mutant in 30 g L⁻¹ SBP hydrolysate without glycerol. These findings highlight the potential of genetically optimized E. coli and optimized hydrolysate conditions to enhance the valorization of agro-industrial waste, supporting future advances in sustainable hydrogen bioeconomy and integrated waste biorefineries. Full article

This study aimed to explore the genetic and functional diversity of Lactiplantibacillus plantarum (Lpb. plantarum) strains from wild fermented foods to identify traits that are useful for food innovation. The growing demand for clean-label, plant-based, and functionally enriched fermented foods exposes the limitations of current industrial fermentation practices, which rely on standardized lactic acid bacteria (LAB) strains with limited metabolic plasticity. This constraint hinders the development of new food formulations and the replacement of conventional additives. To address this gap, 343 LAB strains were analyzed, including 69 Lpb plantarum strains, isolated from five minimally processed, spontaneously fermented matrices: fermented millet, kombucha, and sourdough (plant-based), wild fermented mountain milk, and natural whey starter (animal-based). Whole-genome sequencing was performed to assess phylogenetic relationships and to annotate genes encoding carbohydrate-active enzymes (CAZymes) and antimicrobial compounds. The results revealed a marked strain-level diversity. Glycoside hydrolase (GH) families GH13 and GH1 were widely distributed, while GH25 and GH32 showed variable presence across clusters. Strains grouped into clusters enriched with plant-based isolates exhibited distinct CAZyme profiles adapted to complex carbohydrates. Clusters with animal-based strains exhibited a broader gene repertoire related to bacteriocin biosynthesis. These findings highlight the untapped potential of wild fermented food environments as reservoirs of Lpb. plantarum with unique genomic traits. Harnessing this diversity can expand the functional capabilities of starter cultures, promoting more sustainable, adaptive, and innovative fermentation systems. This study underscores the strategic value of underexploited microbial niches in meeting the evolving demands of modern food production. Full article

Lachancea thermotolerans help increase the acidity of wines by producing L-lactic acid, which can serve as a strategy to mitigate the decrease in total acidity in wines promoted by climate change. The aim of the present paper is to test the capability of wine bioacidification of wild strains isolated from Rioja AOC. For this purpose, L. thermotolerans strains isolated from musts were used in mixed fermentation (co-inoculation and sequential inoculation) with Saccharomyces cerevisiae to determine the fermentation performance and L-lactic acid production, in both laboratory scale and pilot scale. Fermentation kinetics was evaluated, in addition to the final wine chemical composition and organoleptical properties. The results indicated that the isolated strains produced L-lactic acid; these effects were dependent on the strain and the inoculation strategy, being higher the effect in sequential inoculation (9.20 g/L) than in co-inoculation. This L-lactic acid production capacity was maintained at a pilot scale (4.65 g/L), in which the acidity increase was perceptible in the sensorial analysis, and an ethanol concentration decrease was also reported. The wine acidification depends on the appropriate selection of the strains, the inoculation procedure, the yeast adaptation to media, and competence with other yeast species present in the fermentation broth. The wild L. thermotolerans Lt97 strain could be used as a bioacidification tool for wines affected by climate change. Full article

Mexico is home to a rich variety of fermented beverages made from both wild and domesticated plant species. Fermentation practices vary, with producers using either wild or inoculated techniques to obtain culturally valued final products. It is generally assumed that wild fermentations yield a greater diversity of volatile compounds compared to inoculated fermentations, as the latter tend to reduce microbial diversity throughout the process. However, this pattern remains largely unexplored in relation to the volatile profiles of traditionally fermented cactus-based beverages. Despite this assumption, comparative studies examining these profiles across different fermentation methods are scarce, especially given that these beverages are not produced under standardized conditions. To investigate this, we used GC-MS to characterize the aroma profile of colonche, a traditional fermented beverage made primarily from Opuntia streptacantha fruits. Colonche is produced by both wild and inoculated fermentation methods. In addition, a rapid sensory evaluation using the modified Flash Profile (mFP) technique was performed to evaluate flavor differences between the fermentation methods. A total of 55 volatile compounds were identified, with wild fermentations showing greater diversity (55) than inoculated fermentations (50). Most compounds overlapped, but five were unique to spontaneous fermentations, contributing to distinct sensory profiles. The mFP results also indicate that sensory attributes vary by fermentation type, with wild fermentations being more strongly associated with positive descriptors such as taste and smell, while inoculated samples have a distinctly pungent aftertaste. These findings highlight colonche not only as a reservoir of microbial diversity in arid regions but also as a culturally significant beverage with complex sensory attributes. Recognizing and preserving these attributes is essential for safeguarding traditional foodscapes. Full article

Fungal species secrete various enzymes and are considered the primary sources of industrially important cellulases. Cellulases are essential natural factors for cellulose degradation and have attracted significant interest for multiple applications. However, reducing the cost and enhancing cellulase production remains a significant challenge. Mutagenesis has opened a new window for enhancing enzyme secretion by modifying the organism’s genome. In this study, cellulases from Alternaria citri were produced and characterized, and the optimization for ideal fermentation conditions was performed for three types of cellulases (endoglucanase, exoglucanase, and β-glucosidase) by a wild-type (A. citri) and a mutant strain (A. citri 305). Ethyl methanesulfonate, a chemical mutagen, was used to enhance cellulase production by A. citri. The results demonstrate the improved cellulolytic ability of the mutant strain A. citri 305 utilizing lignocellulosic waste substances, particularly, orange-peel powder, wheat straw, sugarcane bagasse, and sawdust, making this study economically valuable. This evokes the potential for multi-dimensional applications in enzyme production, waste degradation, and biofuel generation. This study highlights that the activity of cellulases to hydrolyze various lignocellulosic substrates is enhanced after mutagenesis. Full article

Erythritol has been widely used in the food industry, which predominantly synthesizes it via microbial fermentation, in which Yarrowia lipolytica serves as the preferred candidate chassis strain. However, the wild-type strain of Y. lipolytica exhibits several limitations, including suboptimal industrial performance and elevated levels of by-products, which pose significant challenges in biomanufacturing processes. It is significant to understand the synthesis mechanism of erythritol for improving the capacity of erythritol production by Y. lipolytica. In this study, a mutant exhibiting high erythritol production and stable genetic performance was obtained via a combination of UV and atmospheric and room-temperature plasma mutagenesis. Some key genes related to erythritol production were identified through comparative transcriptome analysis of the mutant strain, revealing significant changes in their expression levels. Individual overexpression of the genes encoding ribose-5-phosphate isomerase, glucose-6-phosphate-1-epimerase, adenylate kinase, and alcohol dehydrogenase in Y. lipolytica Po1g enhanced erythritol production, demonstrating the critical role of each gene in erythritol production. This finding elucidates the molecular mechanism underlying the improved erythritol yield in the mutant strain. The Y. lipolytica mutant C1 produced 194.47 g/L erythritol in a 10 L fermenter with a productivity of 1.68 g/L/h during batch fermentation, surpassing the wild-type strain and reducing the cultivation time by 21 h. It is significant to understand the mechanism of erythritol synthesis for improving erythritol production and its application in industrial-scale production. Full article

cAMP (cyclic adenosine-3′,5′-monophosphate) has extensive physiological functions and nutritional value for living organisms, and it regulates cellular metabolism mainly by modulating PKA (protein kinase A) activity. The current yields of cAMP synthesized by microbial fermentation are still low, which is arousing interest in developing high-yield cAMP strains. In this work, two baker’s yeasts with high cAMP content were constructed by knocking out BCY1, TPK3, and TPK2 genes, and truncating the promoter of the TPK1 gene. The content of cAMP in BN5-126 and BN5-310 (with the TPK1 gene promoter truncated by 126 and 310 bp in BN5) was improved by 30- and 9-fold, respectively, relative to the wild strain. The TPK1 gene mRNA levels of BN5-126 and BN5-310 were decreased by 18% and 40%, respectively, without significant changes in growth performance. The results of heat shock tolerance of engineered strains also reflected the enhanced PKA activity. This work demonstrates a novel strategy for regulating gene expression to boost cAMP biosynthesis in yeast, providing a promising platform for producing nutritionally enriched and functional fermented products. Full article

Pyracantha fortuneana, an underutilized wild plant, has been found to have a high nutritional value. This study used simulated digestion and fecal fermentation models to investigate the digestive properties of the purified acidic pectin polysaccharide of Pyracantha fortuneana and its impact on the gut microbiota and metabolites. Pyracantha fortuneana polysaccharide (PFP) is mainly composed of rhamnose (Rha), galacturonic acid (GalA), glucose (Glc), galactose (Gal), and arabinose (Ara), with a molecular weight (Mw) of 851.25 kDa. Following simulated digestion, the Mw of PFP remained consistent. The reduced sugar content showed minimal change, suggesting that PFP exhibits resistance to gastrointestinal digestion and can effectively reach the colon. Following fecal fermentation, the molecular weight, monosaccharide, and carbohydrate contents of PFP decreased, while the short-chain fatty acid content increased. This suggests that PFP is susceptible to degradation by microorganisms and can be metabolized into acetic acid and n-butyric acid, contributing to the regulation of intestinal health. Meanwhile, PFP promotes the reproduction of beneficial bacteria such as Bacteroides, Dialister, and Dysgonomonas, inhibits the growth of harmful bacteria like Proteus, and generates metabolites such as thiamine, leonuriside A, oxoadipic acid, S-hydroxymethylglutathione, and isonicotinic acid, which exert beneficial effects on human health. These results indicate that PFP has great potential in regulating the gut microbiota and generating beneficial metabolites to promote intestinal functional health and can be used as a prebiotic to prevent diseases by improving intestinal health. Full article