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ABSTRACT Grapes have been cultivated for wine production for millennia. Wine production involves a complex biochemical process where sugars in grape must are converted into alcohol and other compounds by microbial fermentation, primarily by the yeast Saccharomyces cerevisiae. Commercially available S. cerevisiae strains are often used in winemaking, but indigenous (native) strains are gaining attention for their potential to contribute unique flavors. Recent advancements in high-throughput DNA sequencing have revolutionized our understanding of microbial communities during wine fermentation. Indeed, transcriptomic analysis of S. cerevisiae during wine fermentation has revealed a core gene expression program and provided insights into how this yeast adapts to fermentation conditions. Here, we assessed how the age of vines impacts the grape fungal microbiome and used transcriptomics to characterize microbial functions in grape must fermented with commercial and native S. cerevisiae. We discovered that ~130-year-old Zinfandel vines harbor higher fungal loads on their grapes compared to 20-year-old Zinfandel vines, but fungal diversity is similar. Additionally, a comparison of inoculated and uninoculated fermentations showed distinct fungal dynamics, with uninoculated fermentations harboring the yeasts Metschnikowia and Pichia. Transcriptomic analysis revealed significant differences in gene expression between fermentations inoculated and not inoculated with a commercial S. cerevisiae strain. Genes related to metabolism, stress response, and cell adhesion were differentially expressed, indicating varied functionality of S. cerevisiae in these fermentations. These findings provide insights into S. cerevisiae function during fermentation and highlight the potential for indigenous yeast to contribute to wine diversity.IMPORTANCEUnderstanding microbial functions during wine fermentation, particularly the role of Saccharomyces cerevisiae, is crucial for enhancing wine quality. While commercially available S. cerevisiae strains are commonly used, indigenous strains can offer unique flavors, potentially reflecting vineyard terroir. By leveraging high-throughput DNA sequencing and transcriptomic analysis, we explored the impact of vine age on the grape mycobiome and characterized microbial functions during grape fermentation. Our findings revealed that older vines harbor higher fungal loads, but fungal diversity remains similar across vine ages. Additionally, uninoculated fermentations exhibited diverse fungal dynamics, including the beneficial wine yeasts Metschnikowia and Pichia. Transcriptomic analysis uncovered significant differences in S. cerevisiae gene expression between inoculated and uninoculated fermentations, highlighting the potential of indigenous yeast to enhance wine diversity and inform winemaking practices.

Copyright of China Brewing is the property of China Brewing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Aims To compare the species diversity and composition of indigenous yeast communities of hybrid grapes from conventionally and organically cultivated vineyards of an emerging cool-climate wine producing region. Methods and Results Illumina MiSeq sequences from L'Acadie blanc grape musts were processed and filtered to characterize indigenous yeast communities in organic and conventional vineyards of the Annapolis Valley wine region in Nova Scotia, Canada. While cultivation practice was not associated with yeast diversity or species richness, there was a strong effect on yeast community composition, with conventional vineyards characterized by higher proportions of Sporidiobolales and Filobasidium magnum , and organic vineyards supporting Filobasidium species other than F. magnum and higher proportions of Symmetrospora. There was also variation in yeast community composition among individual vineyards, and from year to year. Conclusions This is the first comprehensive assessment of yeasts associated with hybrid grapes grown using different cultivation practices in a North American cool climate wine region. Communities were dominated by basidiomycete yeasts and species composition of these yeasts differed significantly between vineyards employing organic and conventional cultivation practices. The role of basidiomycete yeasts in winemaking is not well understood, but some species may influence wine characteristics. [ABSTRACT FROM AUTHOR]

Abstract Background Purple blotch disease is a devastating disease, resulting in significant yield losses in onion. Application of synthetic fungicides is a rapid approach for the control of this disease, but extensive use of synthetic fungicides results in resistance development in pathogen. Thus, it is mandatory to explore alternative approaches to overcome the fungicide resistance challenges. The present study focused on a sustainable biocontrolling approach by using biocontrol yeast. The objective was to develop a management strategy that offers an environmentally acceptable alternative to commonly used fungicides. Results A total of six pathogenic isolates were obtained from the infected onion leaves, out of all tested isolates, OP-4 recorded as highly virulent with disease incidence (75.2%). Filobasidium wieringae and Pichia kluyveri drastically reduced the in vitro mycelial growth of Alternaria porri (14 and 21 mm, respectively). In the greenhouse experiment, plant inoculated with P. kluyveri suspension was the most effective, resulting in considerable reduction (77.1%) in disease severity, before two days of pathogen inoculation. However, F. wieringae showed a considerable reduction (84.5%) in disease severity when applied in combination with P. kluyveri two days post-inoculation. Conclusions These findings highlighted the strong biocontrol potential of P. kluyveri and F. wieringae in managing the purple blotch disease of onion and can reduce the reliance on synthetic fungicides. Further research and field trials should be conducted to optimize the application methods and evaluate the long-term effectiveness of these bioagents.

The selection of native yeast for alcoholic fermentation in wine focuses on ensuring the success of the process and promoting the quality of the final product. The purpose of this study was firstly to create a large collection of new yeast isolates and categorize them based on their oenological potential. Additionally, the geographical distribution of the most dominant species, Saccharomyces cerevisiae, was further explored. Towards this direction, fourteen spontaneously fermented wines from different regions of Greece were collected for yeast typing. The yeast isolates were subjected in molecular analyses and identification at species level. RAPD (Random Amplified Polymorphic DNA) genomic fingerprinting with the oligo-nucleotide primer M13 was used, combined with Matrix Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry (MALDI-TOF MS) technique. All yeast isolates were scrutinized for their sensitivity to killer toxin, production of non-desirable metabolites such as acetic acid and H2S, β-glucosidase production and resistance to the antimicrobial agent; SO2. In parallel, S. cerevisiae isolates were typed at strain level by interdelta - PCR genomic fingerprinting. S. cerevisiae strains were examined for their fermentative capacity in laboratory scale fermentation on pasteurized grape must. Glucose and fructose consumption was monitored daily and at the final point a free sorting task was conducted to categorize the samples according to their organoleptic profile. According to our results, among the 190 isolates, S. cerevisiae was the most dominant species while some less common non-Saccharomyces species such as Trigonopsis californica, Priceomyces carsonii, Zygosaccharomyces bailii, Brettanomyces bruxellensis and Pichia manshurica were identified in minor abundancies. According to phenotypic typing, most isolates were neutral to killer toxin test and exhibited low acetic acid production. Hierarchical Cluster Analysis revealed the presence of four yeast groups based on phenotypic fingerprinting. Strain level typing reported 20 different S. cerevisiae strains from which 65% indicated fermentative capacity and led to dry wines. Sensory evaluation results clearly discriminated the produced wines and consequently, the proposed yeast categorization was confirmed. A novel approach that employs biostatistical tools for a rapid screening and classification of indigenous wine yeasts with oenological potential, allowing a more efficient preliminary selection or rejection of isolates is proposed. [ABSTRACT FROM AUTHOR]

The selection of native yeast for alcoholic fermentation in wine focuses on ensuring the success of the process and promoting the quality of the final product. The purpose of this study was firstly to create a large collection of new yeast isolates and categorize them based on their oenological potential. Additionally, the geographical distribution of the most dominant species, Saccharomyces cerevisiae, was further explored. Towards this direction, fourteen spontaneously fermented wines from different regions of Greece were collected for yeast typing. The yeast isolates were subjected in molecular analyses and identification at species level. RAPD (Random Amplified Polymorphic DNA) genomic fingerprinting with the oligo-nucleotide primer M13 was used, combined with Matrix Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry (MALDI-TOF MS) technique. All yeast isolates were scrutinized for their sensitivity to killer toxin, production of non-desirable metabolites such as acetic acid and H2S, β-glucosidase production and resistance to the antimicrobial agent; SO2. In parallel, S. cerevisiae isolates were typed at strain level by interdelta – PCR genomic fingerprinting. S. cerevisiae strains were examined for their fermentative capacity in laboratory scale fermentation on pasteurized grape must. Glucose and fructose consumption was monitored daily and at the final point a free sorting task was conducted to categorize the samples according to their organoleptic profile. According to our results, among the 190 isolates, S. cerevisiae was the most dominant species while some less common non-Saccharomyces species such as Trigonopsis californica, Priceomyces carsonii, Zygosaccharomyces bailii, Brettanomyces bruxellensis and Pichia manshurica were identified in minor abundancies. According to phenotypic typing, most isolates were neutral to killer toxin test and exhibited low acetic acid production. Hierarchical Cluster Analysis revealed the presence of four yeast groups based on phenotypic fingerprinting. Strain level typing reported 20 different S. cerevisiae strains from which 65% indicated fermentative capacity and led to dry wines. Sensory evaluation results clearly discriminated the produced wines and consequently, the proposed yeast categorization was confirmed. A novel approach that employs biostatistical tools for a rapid screening and classification of indigenous wine yeasts with oenological potential, allowing a more efficient preliminary selection or rejection of isolates is proposed.

Our current research aimed to investigate the impacts of the use of indigenous yeast Saccharomyces cerevisiae with different amounts of Lachancea thermotolerans yeasts in mixed culture on the general composition, aroma compounds, sensory analysis and yeast growth of cv. Emir wine. The utilization of L. thermotolerans in mixed cultures reduced the total acidity of wines from 5.40 to 5.19 g/L (as tartaric acid). The acidity of high acid grapes musts obtained from various viticulture areas can be relatively decreased in wine production. In addition, there may be a slight decrease in the amount of ethyl alcohol. On the other hand, increasing the inoculum level of L. thermotolerans led to an increase in the amount of higher alcohols. However, the concentration of esters declined with the higher inoculum levels. According to the sensory evaluation, the most preferred wine was the one obtained with co-inoculation of S. cerevisiae and L. thermotolerans strains at the level of 5×106 and 1×108 cells/mL, respectively. As a result, it can be said that the use of L. thermotolerans yeast in different inoculum levels has a positive effect on wine fermentation.

ABSTRACT: Indigenous microorganisms are important components of the complex ecosystem of many dairy foods including cheeses, and they are potential contributors to the development of a specific cheese's sensory properties. Among these indigenous microorganisms are the yeasts Cyberlindnera jadinii, Pichia kudriavzevii, and Kazachstania servazzii, which were previously detected using traditional microbiological methods in both raw milk and some artisanal specialty cheeses produced in the province of Québec, Canada. However, their levels across different cheese varieties are unknown. A highly specific and sensitive real-time quantitative PCR assay was developed to quantitate these yeast species in a variety of specialty cheeses (bloomy-rind, washed-rind, and natural-rind cheeses from raw, thermized, and pasteurized milks). The specificity of the quantitative PCR assay was validated, and it showed no cross-amplification with 11 other fungal microorganisms usually found in bloomy-rind and washed-rind cheeses. Cyberlindnera jadinii and P. kudriavzevii were found in the majority of the cheeses analyzed (25 of 29 and 24 of 29 cheeses, respectively) in concentrations up to 104 to 108 gene copies/g in the cheese cores, which are considered oxygen-poor environments, and 101 to 104 gene copies/cm2 in the rind. However, their high abundance was not observed in the same samples. Whereas C. jadinii was present and dominant in all core and rind samples, P. kudriavzevii was mostly present in cheese cores. In contrast, K. servazzii was present in the rinds of only 2 cheeses, in concentrations ranging from 101 to 103 gene copies/cm2, and in 1 cheese core at 105 gene copies/g. Thus, in the ecosystems of specialty cheeses, indigenous yeasts are highly frequent but variable, with certain species selectively present in specific varieties. These results shed light on some indigenous yeasts that establish during the ripening of specialty cheeses.

Ninety-two wild yeasts were isolated from different fruits, for possible use in brewing, using the technological traits of carbohydrate fermentation and hydrogen sulfide production. Twelve yeasts were selected for identification by sequencing (D1/D2 domain or ITS1-5.8S-ITS2 region) and their volatile compounds production analyzed using gas chromatography. From these analyses, three yeasts were chosen for further characterization and beer production. Strains were characterized by their tolerance to osmotic and ethanol stress, their flocculation profile, growth at different temperatures, apparent attenuation (percentage of sugars converted into alcohol), estimated ABV (alcohol by volume) and reducing sugar profile. Beers were analyzed for alcohol content and sensorial analysis. The isolates CL011 and PB111 (Saccharomyces cerevisiae) and CB341 (Wickerhamomyces anomalus) showed promising properties for brewing, which included high production of interesting volatile compounds (esters, terpenes, lactones, and C13-norisoprenoids) by CL011, a neutral profile by PB111, and the production of non-classic beer volatile compounds by CB341 in a mixed culture. Supplemental data for this article is available online at https://doi.org/10.1080/03610470.2022.2031777. [ABSTRACT FROM AUTHOR]

Yeast assimilable nitrogen (YAN) is one of the important factors affecting yeast growth and metabolism. However, the nitrogen requirement of indigenous commercial S. cerevisiae NX11424 is unclear. In this study, metabolomics was used to analyze the metabolite profiles of the yeast strain NX11424 under high (433 mg/L) and low (55 mg/L) YAN concentrations. It was found that yeast biomass exhibited different trends under different YAN conditions and was generally positively correlated with the initial YAN concentration, while changes of key biomarkers of yeast strain NX11424 at different stages of fermentation showed a similar trend under high and low YAN concentrations. The YAN concentration affected the metabolite levels of the yeast strain NX11424, which resulted in the significant difference in the levels of pyruvic acid, α-oxoglutarate, palmitoleic acid, proline, butane-2,3-diol, citrulline, ornithine, galactinol, citramalic acid, tryptophan, alanine, phosphate and phenylethanol, mainly involving pathways such as central carbon metabolism, amino acid metabolism, fatty acid metabolism, purine metabolism, and energy metabolism. Yeast strain NX11424 could utilize proline to produce protein under a low YAN level. The intracellular level of citrulline and ornithine under high YAN concentration was higher than that under low YAN level. Yeast strain NX11424 is more suitable for fermentation at lower YAN level. The results obtained here will help to rational utilize of YAN by S. cerevisiae NX11424, and is conducive to precise control of the alcohol fermentation and improve wine quality. • Initial YAN level significantly affected the metabolite profiles of NX11424. • NX11424 could utilize proline for protein synthesis under low YAN level. • The intracellular levels of citrulline and ornithine were higher under high YAN condition. • NX11424 is more suitable for fermentation at lower YAN level (55 mg/L). [ABSTRACT FROM AUTHOR]

The object of this study was to compare the effects of three indigenous non- Saccharomyces cerevisiae strains (Hanseniaspora uvarum, Metschnikowia sinensis and Rhodotorula mucilaginosa) and their paired (co-inoculated) fermentation on the microbial communities and volatile profiles during the fermentation of Marselan wine. Results showed that both monoculture and mixed fermentation with non- Saccharomyces strain can complete alcohol fermentation wherein the alcohol content of indigenous yeast treatments were significantly higher than that of control NSD. A total of 44 aroma compounds were identified in all samples, among which the H + R mixed inoculation showed the highest aroma content (28581±1576.61 μg/L). In particular, the contents of ethyl butyrate (V5), ethyl octanoate (V9), and ethyl decanoate (V11) were significantly high, which could enhance the fresh fruit aroma in Marselan wine. Microbial diversity analysis showed that the diversity of fungi between groups was greater than that of bacteria, and H + R (Hanseniaspora and Rhodotorula) had higher microbial abundance (bacteria 79, fungi 78) than the other groups. Spearman correlation analysis revealed that Fructobacillus , Acinetobacter , and other indigenous microorganisms were positively correlated with volatile substances. In summary, the mixed fermentation of Hanseniaspora and Rhodotorula can be considered an effective strategy for improving the aroma quality of Marselan wine. This study provides new insight and useful references for the role and application of native non- Saccharomyces yeast in wine making. • Impact of pure and pairwise fermentation of non-Saccharomyces yeast on Marselan wine. • Co-inoculation of Hanseniaspora & Rhodotorula yeasts enhance the ester aroma content. • Co-inoculation of Hanseniaspora & Rhodotorula yeasts enrich the microbiota diversity. • Different native non-Saccharomyces yeasts exhibited different flavor characteristics. [ABSTRACT FROM AUTHOR]

Wine fermentations are generally completed by the domestic yeast Saccharomyces cerevisiae, but many indigenous vineyard yeasts also influence wine flavour and aroma. Despite the flourishing wine industry in Nova Scotia, there has yet to be any systematic evaluation of these yeasts in Atlantic Canada. The yeast communities of pressed L'Acadie blanc grapes sampled from an organic vineyard in the Annapolis Valley in 2018 and 2019 were characterized before and after spontaneous fermentation by both Illumina and PacBio sequencing, to address and compare potential platform biases. Chemical and sensory evaluations were also conducted. Basidiomycete yeasts, including Vishniacozyma carnescens, Filobasidium globisporum, and Curvibasidium cygneicollum, dominated pre-fermentation diversity. Species of Saccharomyces made up ∼0.04% of sequences prior to fermentation, but 85%–100% after fermentation, with some replicates dominated by S. cerevisiae and some by S. uvarum. PacBio sequencing detected high proportions of Hanseniaspora uvarum, while Illumina sequencing did not. A better understanding of Nova Scotia vineyard yeast communities will allow local wine makers to make better use of non-traditional yeasts and spontaneous fermentations to produce high-quality wines unique to the region. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Chinese Institute of Food Science & Technology / Zhongguo Shipin Xuebao is the property of Journal of Chinese Institute of Food Science & Technology Periodical Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Indigenous microorganisms are important components of the complex ecosystem of many dairy foods including cheeses, and they are potential contributors to the development of a specific cheese's sensory properties. Among these indigenous microorganisms are the yeasts Cyberlindnera jadinii , Pichia kudriavzevii , and Kazachstania servazzii , which were previously detected using traditional microbiological methods in both raw milk and some artisanal specialty cheeses produced in the province of Québec, Canada. However, their levels across different cheese varieties are unknown. A highly specific and sensitive real-time quantitative PCR assay was developed to quantitate these yeast species in a variety of specialty cheeses (bloomy-rind, washed-rind, and natural-rind cheeses from raw, thermized, and pasteurized milks). The specificity of the quantitative PCR assay was validated, and it showed no cross-amplification with 11 other fungal microorganisms usually found in bloomy-rind and washed-rind cheeses. Cyberlindnera jadinii and P. kudriavzevii were found in the majority of the cheeses analyzed (25 of 29 and 24 of 29 cheeses, respectively) in concentrations up to 104 to 108 gene copies/g in the cheese cores, which are considered oxygen-poor environments, and 101 to 104 gene copies/cm2 in the rind. However, their high abundance was not observed in the same samples. Whereas C. jadinii was present and dominant in all core and rind samples, P. kudriavzevii was mostly present in cheese cores. In contrast, K. servazzii was present in the rinds of only 2 cheeses, in concentrations ranging from 101 to 103 gene copies/cm2, and in 1 cheese core at 105 gene copies/g. Thus, in the ecosystems of specialty cheeses, indigenous yeasts are highly frequent but variable, with certain species selectively present in specific varieties. These results shed light on some indigenous yeasts that establish during the ripening of specialty cheeses. [ABSTRACT FROM AUTHOR]

Grapes have been cultivated for wine production for millennia. Wine production involves a complex biochemical process where sugars in grape must are converted into alcohol and other compounds by microbial fermentation, primarily by the yeast Saccharomyces cerevisiae . Commercially available S. cerevisiae strains are often used in winemaking, but indigenous (native) strains are gaining attention for their potential to contribute unique flavors. Recent advancements in high-throughput DNA sequencing have revolutionized our understanding of microbial communities during wine fermentation. Indeed, transcriptomic analysis of S. cerevisiae during wine fermentation has revealed a core gene expression program and provided insights into how this yeast adapts to fermentation conditions. Here, we assessed how the age of vines impacts the grape fungal microbiome and used transcriptomics to characterize microbial functions in grape must fermented with commercial and native S. cerevisiae . We discovered that ~130-year-old Zinfandel vines harbor higher fungal loads on their grapes compared to 20-year-old Zinfandel vines, but fungal diversity is similar. Additionally, a comparison of inoculated and uninoculated fermentations showed distinct fungal dynamics, with uninoculated fermentations harboring the yeasts Metschnikowia and Pichia . Transcriptomic analysis revealed significant differences in gene expression between fermentations inoculated and not inoculated with a commercial S. cerevisiae strain. Genes related to metabolism, stress response, and cell adhesion were differentially expressed, indicating varied functionality of S. cerevisiae in these fermentations. These findings provide insights into S. cerevisiae function during fermentation and highlight the potential for indigenous yeast to contribute to wine diversity., Importance: Understanding microbial functions during wine fermentation, particularly the role of Saccharomyces cerevisiae , is crucial for enhancing wine quality. While commercially available S. cerevisiae strains are commonly used, indigenous strains can offer unique flavors, potentially reflecting vineyard terroir. By leveraging high-throughput DNA sequencing and transcriptomic analysis, we explored the impact of vine age on the grape mycobiome and characterized microbial functions during grape fermentation. Our findings revealed that older vines harbor higher fungal loads, but fungal diversity remains similar across vine ages. Additionally, uninoculated fermentations exhibited diverse fungal dynamics, including the beneficial wine yeasts Metschnikowia and Pichia. Transcriptomic analysis uncovered significant differences in S. cerevisiae gene expression between inoculated and uninoculated fermentations, highlighting the potential of indigenous yeast to enhance wine diversity and inform winemaking practices., Competing Interests: The authors declare no conflict of interest.

Inulinase enzyme (EC 3.2.1.80) is an enzyme capable of hydrolyzing inulin and is used as a catalyst in the production of High Fructose Syrup (HFS) and fructooligosaccharides (FOS). Inulinase enzymes can be produced by yeasts found in waste such as kepok banana peels (Musa acuminata x balbisiana). The aims of this study were to obtain the inulinase enzymeproducing yeast from kepok banana peels and to determine the effect of commercial inulin concentration and incubation time on enzyme activity. This research was conducted experimentally using a factorial completely randomized design with factors being inulin concentration of 1% (K1), 3% (K2) and 5% (K3) and incubation time of 6th (W1), 12th (W2), 18th (W3), and 24th hours (W4). The results showed that there were 4 isolates of inulinolytic yeasts obtained from kepok banana peels, namely YP1, YP2, YP4, and YP6. However, the most potential isolate to be used in inulinase production was YP2 isolate because it had the highest inulinolytic ratio value of 1.96. The results of inulinase activity showed that only inulin substrate with concentration of 5% (K3) had a significant or significant effect on inulinase production. [ABSTRACT FROM AUTHOR]

A total of 296 isolates of Saccharomyces cerevisiae sampled from naturally fermenting grape musts from various locations in Lebanon were typed by interdelta fingerprinting. Of these, 88 isolates were compared with oenological strains originating from various countries, using microsatellite characterization at six polymorphic loci. These approaches evidenced a large diversity of the natural oenological Lebanese flora over the territory as well as in individual spontaneous fermentations. Several cases of dominance and perenniality of isolates were observed in the same wineries, where fermentations appeared to involve lineages of sibling isolates. Our work thus evidenced a "winery effect" on strains' relatedness. Similarly, related or identical strains were also detected in vicinal wineries, suggesting strain circulation within small geographical areas and a further "vicinity effect". Moreover, and despite its diversity, the Lebanese flora seemed interrelated, on the basis of microsatellite loci analysis, in comparison to worldwide communities. We finally tested the ability of 21 indigenous strains to act as potential starters for winemaking. Seven of them passed our pre-selection scheme and two of them at least may be good candidates for use provided pilot-scale assays confirm their suitability. [ABSTRACT FROM AUTHOR]

The aim of the study was the physicochemical characterization of wines produced using indigenous yeasts isolated from spontaneously fermented grape musts, obtained from cold climate grapes. Saccharomyces cerevisiae MH020215 and Nakawazaea ishiwadae MG971259 yeast strains were used in this study. The musts obtained from white and red grapes of Johanniter and regent varieties were used as a fermentation raw material. In the produced wines, content of ethyl alcohol, total extract, sugars, free amino nitrogen was analyzed, along with determination of total and volatile acidity and volatile compounds profile. Additionally, organoleptic evaluation was performed. Wines obtained with native S. cerevisiae MH020215 strains were characterized with more favorable enological properties. Synthesis of desirable volatile compounds, especially esters, contributed to the creation of desirable aromatic profile of those wines. Moreover, those beverages contained higher levels of carbonyl compounds (especially acetaldehyde) and lower methanol content. Wines obtained using N. ishiwadae MG971259 cultures were represented by high total acidity level and substantial fusel alcohol content (mainly butanol, propanol), which resulted in an unfavorable sensory profile of the product. [ABSTRACT FROM AUTHOR]

Chromium, ranking the second most among toxic heavy metal pollutants in the world, causing respiratory, cardiovascular and renal problems in human beings is under study herein. We examined the biological remediation of the carcinogenic Cr (VI) polluted soils by indigenous yeast isolates. The total element analysis of the treated sample was determined by Energy Dispersion X-ray Micro Analysis (EDXMA). The sample under study was observed to have a high concentration of 458.29 mgKg−1 Cr (VI), determined by Atomic Absorption Spectroscopy (AAS) and DPC analysis. The most tolerant isolate designated as CSR was used for in vitro and ex-situ bioremediation studies of Cr (VI). The isolate achieved significant bioremediation of 86% in vitro and 75.12% in ex-situ method. The optimal conditions for in vitro bioremediation were found to be 28 °C and a pH of 6. The ITS1, 5.8S rRNA and D1, D2 domain of LSU rRNA gene characterization of the isolate CSR illustrated that it belongs to Ustilago genera. The isolate was deposited in NCBI GenBank as Ustilago sp. CSR (KY284846). Although, Ustilago is generally a pathogenic fungus, our study opens up the scope of using Ustilago spp. for bioremediation of the carcinogenic heavy metal Chromium. [ABSTRACT FROM AUTHOR]

A total of 296 isolates of Saccharomyces cerevisiae sampled from naturally fermenting grape musts from various locations in Lebanon were typed by interdelta fingerprinting. Of these, 88 isolates were compared with oenological strains originating from various countries, using microsatellite characterization at six polymorphic loci. These approaches evidenced a large diversity of the natural oenological Lebanese flora over the territory as well as in individual spontaneous fermentations. Several cases of dominance and perenniality of isolates were observed in the same wineries, where fermentations appeared to involve lineages of sibling isolates. Our work thus evidenced a “winery effect” on strains’ relatedness. Similarly, related or identical strains were also detected in vicinal wineries, suggesting strain circulation within small geographical areas and a further “vicinity effect”. Moreover, and despite its diversity, the Lebanese flora seemed interrelated, on the basis of microsatellite loci analysis, in comparison to worldwide communities. We finally tested the ability of 21 indigenous strains to act as potential starters for winemaking. Seven of them passed our pre-selection scheme and two of them at least may be good candidates for use provided pilot-scale assays confirm their suitability.

Abstract Wine fermentations typically involve the yeast Saccharomyces cerevisiae. However, many other yeast species participate to the fermentation process, some with interesting oenological traits. In this study the species Torulaspora delbrueckii , used occasionally in mixed or sequential fermentation with S. cerevisiae to improve wine sensory profile, was investigated to understand the physiological differences between the two. Next generation sequencing was used to characterize the transcriptome of T. delbrueckii and highlight the different genomic response of these yeasts during growth under wine-like conditions. Of particular interest were the basic differences in the glucose fermentation pathway and the formation of aromatic and flavour compounds such as glycerol, esters and acetic acid. Paralog genes were missing in glycolysis and glycerol biosynthesis in T. delbrueckii. Results indicate the tendency of T. delbrueckii to produce less acetic acid relied on a higher expression of alcoholic fermentation related genes, whereas acetate esters were influenced by the absence of esterases, ATF1 – 2. Additionally, in the Δbap2 S. cerevisiae strain, the final concentration of short branched chain ethyl esters (SBCEEs) was related to branched chain amino acid (BCAA) uptake. In conclusion, different adaption strategies are apparent for T. delbrueckii and S. cerevisiae yeasts, an understanding of which will allow winemakers to make better use of such microbial tools to achieve a desired wine sensory outcome. Highlights • Torulaspora delbrueckii confirmed its ability to produce lower acetate. • Torulaspora Delbrueckii is missing multiple genes resulting in lower production of higher alcohols and acetate esters. • Branched chain amino acid permease BAP2 transcript expression is related to short ethyl ester production in S. cerevisiae. [ABSTRACT FROM AUTHOR]

In order to improve the slow ethanol fermentation during acetic acid fermentation process of black raspberry vinegar (BRV), the microbiological and physicochemical aspects of the effects of indigenous Saccharomyces cerevisiae JBCC-21A were examined. The selected S. cerevisiae JBCC-21A showed better growth and ethanol production rates than the commercial yeast strains. The ethanol production rate was 3-times faster than the traditional method. Acetic acid fermentation by S. cerevisiae JBCC-21A began 10 days earlier than the traditional method and reached up to 60 g/L acetic acid. Bacterial counts revealed Acetobacter pasteurianus was the only dominant species throughout the inoculated acetic acid fermentation. The physicochemical and functional properties of the fermented vinegar using indigenous S. cerevisiae JBCC-21A maintained a high quality similar to the traditional method, while being the faster fermentation process. Thus, it is suggested that inoculation of the indigenous S. cerevisiae strain in order to shorten the fermentation time without affecting the quality of traditional BRV. [ABSTRACT FROM AUTHOR]

Highlights • Sun-dried grape musts were fermented by co-inoculation of indigenous strains. • Lachancea thermotolerans strain tolerates and ferments high-sugar must. • Multivariate Curve Resolution is a suitable tool for wine volatile profile processing. • Wines volatile profile depended on the ratio of each yeast strain in the inoculum. • Co-inoculated fermentations seem to increase aromatic complexity in wines. Abstract The aim of this work was to evaluate how the use of mixed cultures of Saccharomyces cerevisiae and Lachancea thermotolerans indigenous yeast strains influences the volatile composition of wine. Multivariate curve resolution (MCR) method has been applied to data analysis. Five fermentation trials were carried out: three co-inoculated with L. thermotolerans:S. cerevisiae , at the ratio of 50:1, 20:1 and 5:1 respectively, and two with a pure culture of each strain. A must from sun-dried Pedro Ximénez grapes was employed. Volatile composition was determined by dual sequential stir bar sorptive extraction, followed by GC–MS analysis. MCR provided 171 peaks. Results in co-inoculation fermentations revealed that the majority compounds obtained in each case followed the same trend as that observed for the pure culture of the strain that was present in a higher proportion. Finally, 50:1 and 20:1 seemed to be the best proportions to obtain a wine with a quality volatile profile. [ABSTRACT FROM AUTHOR]

Commercial yeasts are normally used in the wine industry to achieve stable and enhanced wine flavors and aromas, but they can lead to a loss of diversity and a peculiar regional wine style. An indigenous commercial wine yeast, CECA, has been isolated from a well-known wine-producing region, Ningxia, China. As CECA is a young commercial yeast, further research into its characteristics is required. In this study, the performance of CECA in Cabernet Sauvignon wine fermentation, three different fermentation treatments, spontaneous without inoculation, inoculated with CECA, and inoculated with CECA after treatment of the grape must with dimethyl dicarbonate, were performed. During fermentation, six species of yeast identified through a culture-dependent method were also identified with a culture-independent method, although the relative abundance differed between the methods. The floral and fruity were confirmed as characteristics of CECA-inoculated wines using headspace solid-phase microextraction-gas chromatography-mass spectrometry and sensory evaluation. This study enables winemakers to better understand an indigenous commercial yeast, make a peculiar aroma for Ningxia wines and promote the reputation of Ningxia region. • The fermentation characteristics of a young indigenous commercial CECA yeast from Ningxia wine-producing region was studied. • Six yeast species were identified using culture-dependent and -independent method. • Floral and fruity were confirmed to be the typical aromas and flavors of CECA based on HS-SPME-GC-MS and OAVs evaluation. [ABSTRACT FROM AUTHOR]

Yeast communities associated with Vitis vinifera L. ecosystems have been widely characterized. Less is known, however, about yeast communities present in grapes and fermenting musts from Vitis non-vinifera ecosystems. Moreover, there are no comparative studies concerning yeast communities in grapes from V. vinifera L. and non-vinifera Vitis species in vineyards from a shared terroir. In this work, we have used a culture-dependent strategy, phenotypic analyses, and molecular genotyping, to study the most representative yeast species present in spontaneously fermenting musts of grapes harvested from neighboring V. vinifera L. (cv. Malbec) and V. labrusca L. (cv. Isabella) vineyards. Phenotypic analyses of H2S production, ethanol tolerance and carbon utilization, on randomly selected strains of each Hanseniaspora uvarum, Starmerella bacillaris and Saccharomyces cerevisiae strains, as well as microsatellite genotyping of S. cerevisiae isolates from each the Malbec and Isabella grape musts, suggest that V. vinifera L. and V. labrusca L. ecosystems could harbor different yeast strain populations. Thus, microbial communities in exotic Vitis species may offer opportunities to look for unique yeast strains that could not be present in conventional V. vinifera L. ecosystems.

In this research, 20 Saccharomyces cerevisiae isolates obtained during spontaneous fermentation of ‘Kalecik Karasi’ and ‘Emir’ grapes were evaluated for their technological characteristics. All of the S. cerevisiae isolates could grow at the tested temperatures, pH values and sugar concentration. Most of the tested isolates (80%) produced the same level of H2S than the control culture. All indigenous S. cerevisiae isolates showed similar carbon assimilation and fermentation profiles, with a few exceptions. Only one isolate (E/S6) was found to have proteolytic activity. The killer phenotype was detected in KK/FS11 isolate. KK/FS3, E/FS12, E/S7 and E/S8 isolates were neutral as to killer phenotype. While only three isolates could tolerate high concentration of ethanol (14%; v/v), 11 isolates could grow in the media containing 200 mg SO2/L. In addition, some of the isolates were distinguished among the others because of their ability to secrete enzyme(s) which may provide advantages for producing wines with specific aromatic characteristics. When some of the tested technological characteristics and enzymatic profiles were evaluated together, four isolates (KK/S17, E/S6, E/S9 and E/FS12) distinguished from others with respect to their superior characteristics, which have potential for further investigation in order to produce wines with specific aroma for Capadoccia region.

The selection of native yeast for alcoholic fermentation in wine focuses on ensuring the success of the process and promoting the quality of the final product. The purpose of this study was firstly to create a large collection of new yeast isolates and categorize them based on their oenological potential. Additionally, the geographical distribution of the most dominant species, Saccharomyces cerevisiae , was further explored. Towards this direction, fourteen spontaneously fermented wines from different regions of Greece were collected for yeast typing. The yeast isolates were subjected in molecular analyses and identification at species level. RAPD (Random Amplified Polymorphic DNA) genomic fingerprinting with the oligo-nucleotide primer M13 was used, combined with Matrix Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry (MALDI-TOF MS) technique. All yeast isolates were scrutinized for their sensitivity to killer toxin, production of non-desirable metabolites such as acetic acid and H 2 S, β-glucosidase production and resistance to the antimicrobial agent; SO 2 . In parallel, S. cerevisiae isolates were typed at strain level by interdelta - PCR genomic fingerprinting. S. cerevisiae strains were examined for their fermentative capacity in laboratory scale fermentation on pasteurized grape must. Glucose and fructose consumption was monitored daily and at the final point a free sorting task was conducted to categorize the samples according to their organoleptic profile. According to our results, among the 190 isolates, S. cerevisiae was the most dominant species while some less common non-Saccharomyces species such as Trigonopsis californica, Priceomyces carsonii , Zygosaccharomyces bailii, Brettanomyces bruxellensis and Pichia manshurica were identified in minor abundancies. According to phenotypic typing, most isolates were neutral to killer toxin test and exhibited low acetic acid production. Hierarchical Cluster Analysis revealed the presence of four yeast groups based on phenotypic fingerprinting. Strain level typing reported 20 different S. cerevisiae strains from which 65% indicated fermentative capacity and led to dry wines. Sensory evaluation results clearly discriminated the produced wines and consequently, the proposed yeast categorization was confirmed. A novel approach that employs biostatistical tools for a rapid screening and classification of indigenous wine yeasts with oenological potential, allowing a more efficient preliminary selection or rejection of isolates is proposed., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Tzamourani, Taliadouros, Paraskevopoulos and Dimopoulou.)

Yeast communities associated with Vitis vinifera L. ecosystems have been widely characterized. Less is known, however, about yeast communities present in grapes and fermenting musts from Vitis non-vinifera ecosystems. Moreover, there are no comparative studies concerning yeast communities in grapes from V. vinifera L. and non-vinifera Vitis species in vineyards from a shared terroir. In this work, we have used a culture-dependent strategy, phenotypic analyses, and molecular genotyping, to study the most representative yeast species present in spontaneously fermenting musts of grapes harvested from neighboring V. vinifera L. (cv. Malbec) and V. labrusca L. (cv. Isabella) vineyards. Phenotypic analyses of H2S production, ethanol tolerance and carbon utilization, on randomly selected strains of each Hanseniaspora uvarum, Starmerella bacillaris and Saccharomyces cerevisiae strains, as well as microsatellite genotyping of S. cerevisiae isolates from each the Malbec and Isabella grape musts, suggest that V. vinifera L. and V. labrusca L. ecosystems could harbor different yeast strain populations. Thus, microbial communities in exotic Vitis species may offer opportunities to look for unique yeast strains that could not be present in conventional V. vinifera L. ecosystems. [ABSTRACT FROM AUTHOR]

Verdicchio, Passerina and Pecorino are native grape cultivars of the Marche region, cultivated in winemaking area of Ascoli Piceno, in central Italy. In particular, Passerina and Pecorino varieties have been abandoned and forgotten for a long time and only in recent years are rediscovered and appreciated. Here, two indigenous yeasts, isolated from grapes of Verdicchio and Pecorino varieties and identified as Saccharomyces cerevisiae, were evaluated and compared with commercial starters cultures widely used for the vinification of Piceno DOC (Denominazione Origine Controllata) area at industrial scale. A polyphasic approach, including yeast genotyping, phenotypic traits evaluation and fermentative performance in natural grape juice, was applied to evaluate the fitness of strains. Using interdelta primers, the two selected cultures showed a unique profile while the results of microvinifications showed that both indigenous strains exhibited good enological parameters and fermentative aptitude comparable with that shown by commercial strains used as controls. The profile of volatile compounds of wines of indigenous strains was characterized by a significant high production of isoamyl acetate and ethyl esters at 22 °C and phenyl ethyl acetate at 16 °C. Overall results indicate that the two indigenous selected yeasts showed a genetic and phenotypic specificity and they could be profitably used to characterize the Piceno DOC area wines. [ABSTRACT FROM AUTHOR]

The use of non-Saccharomyces yeast for wine making is becoming a common trend in many innovative wineries. The application is normally aimed at increasing aromas, glycerol, reducing acidity, and other improvements. This manuscript focuses on the reproduction of the native microbiota from the vineyard in the inoculum. Thus, native selected yeasts (Hanseniaspora uvarum, Metschnikowia pulcherrima, Torulaspora delbrueckii, Starmerella bacillaris species and three different strains of Saccharomyces cerevisiae) were inoculated sequentially, or only S. cerevisiae (three native strains together or one commercial) was used. Inoculations were performed both in laboratory conditions with synthetic must (400 mL) as well as in industrial conditions (2000 kg of grapes) in red winemaking in two different varieties, Grenache and Carignan. The results showed that all the inoculated S. cerevisiae strains were found at the end of the vinifications, and when non-Saccharomyces yeasts were inoculated, they were found in appreciable populations at mid-fermentation. The final wines produced could be clearly differentiated by sensory analysis and were of similar quality, in terms of sensory analysis panelists’ appreciation.

Whey, by product from cheese production, having high content of protein, can be a source of indigineous yeast with proteolytic activity. This research aims to identify indigenous yeasts with proteolytic activity from homemademozzarella cheese whey. There were 2 kinds of whey collected throughout the making of mozzarella, the first whey was collected after the coagulation process and the second whey was collected after mozzarella curdling process. Each types of whey were inoculated into Potato Dextrose Agar (PDA) media modified with 3% yeast extract and 10 ppm Amoxicillin and were further incubated for 48 hours in room temperature. Each colony formed were then differentiated macroscopically and purified in a separate modified PDA media for 4 times. Purified colonies were further identified under microscope and only the colonies having yeasts morphology were tested for its proteolytic activity with paving block method using Nutrient Agar plus 3% Skim Milk, with formation of clear zone were measured as proteolytic activity. Yeasts with proteolytic activity were identified using RapID yeast plus system. The results showed 7 yeasts colonies found and proteolytic activity was only found in 1 isolate with ±9.5 mm diameter of clear zone. The isolate was further brought to identification and revealed as Trichosporon beigelii. [ABSTRACT FROM AUTHOR]

The use of non-Saccharomyces yeast for wine making is becoming a common trend in many innovative wineries. The application is normally aimed at increasing aromas, glycerol, reducing acidity, and other improvements. This manuscript focuses on the reproduction of the native microbiota from the vineyard in the inoculum. Thus, native selected yeasts (Hanseniaspora uvarum, Metschnikowia pulcherrima, Torulaspora delbrueckii, Starmerella bacillaris species and three different strains of Saccharomyces cerevisiae) were inoculated sequentially, or only S. cerevisiae (three native strains together or one commercial) was used. Inoculations were performed both in laboratory conditions with synthetic must (400 mL) as well as in industrial conditions (2000 kg of grapes) in red winemaking in two different varieties, Grenache and Carignan. The results showed that all the inoculated S. cerevisiae strains were found at the end of the vinifications, and when non-Saccharomyces yeasts were inoculated, they were found in appreciable populations at mid-fermentation. The final wines produced could be clearly differentiated by sensory analysis and were of similar quality, in terms of sensory analysis panelists' appreciation. [ABSTRACT FROM AUTHOR]

Verdicchio, Passerina and Pecorino are native grape cultivars of the Marche region, cultivated in winemaking area of Ascoli Piceno, in central Italy. In particular, Passerina and Pecorino varieties have been abandoned and forgotten for a long time and only in recent years are rediscovered and appreciated. Here, two indigenous yeasts, isolated from grapes of Verdicchio and Pecorino varieties and identified as Saccharomyces cerevisiae, were evaluated and compared with commercial starters cultures widely used for the vinification of Piceno DOC (Denominazione Origine Controllata) area at industrial scale. A polyphasic approach, including yeast genotyping, phenotypic traits evaluation and fermentative performance in natural grape juice, was applied to evaluate the fitness of strains. Using interdelta primers, the two selected cultures showed a unique profile while the results of microvinifications showed that both indigenous strains exhibited good enological parameters and fermentative aptitude comparable with that shown by commercial strains used as controls. The profile of volatile compounds of wines of indigenous strains was characterized by a significant high production of isoamyl acetate and ethyl esters at 22 °C and phenyl ethyl acetate at 16 °C. Overall results indicate that the two indigenous selected yeasts showed a genetic and phenotypic specificity and they could be profitably used to characterize the Piceno DOC area wines.

The potential applications of wild yeast strains with β-glucosidase activity were investigated by assaying their enzymatic production under simulated oenological conditions, coupled with the exploration of the potential applications of the β-glucosidases by studying the enzymatic activity and stability under similar oenological conditions. The assay of enzymatic locations revealed that the β-glucosidase activities from these wild strains occurred in the extracellular fraction, and in whole and permeabilized cells. The effects of different oenological factors on β-glucosidase production indicated that the F6 Trichosporon asahii strain had higher β-glucosidase production than the other strains under low pH conditions. However, the F35 Hanseniaspora uvarum strain and the F30 Saccharomyces cerevisiae strain showed higher β-glucosidase production under high-sugar conditions. Furthermore, the influence of oenological factors on the activity and stability of the β-glucosidases revealed that the enzyme from the F6 T. asahii strain had a stronger low-pH-value resistance than the other yeast β-glucosidases. These results suggest that the F35 H. uvarum, F30 S. cerevisiae and the F6 T. asahii β-glucosidases may have some potentially applicable values in the fermentation industry. Copyright © 2015 The Institute of Brewing & Distilling [ABSTRACT FROM AUTHOR]

This study deals with understanding the effects of salt reduction on both the physicochemical and microbiological properties of soy sauce fermentation and also the application of indigenous yeast starters to compensate for undesirable changes occurring in salt-reduced processes. Fermentation was tested in situ at a Korean commercial soy sauce processing unit. Salt reduction resulted in higher acidity as well as lower pH and contents of residual sugar and ethanol. Moreover, undesired flavor characteristics, due to a lack of distinctive compounds, was observed. In addition, putrefactive Staphylococcus and Enterococcus spp. were present only during salt-reduced fermentation. To control these adverse effects, a single or mixed culture of two indigenous yeasts, Torulaspora delbrueckii and Pichia guilliermondii , producing high ethanol and 3-methyl-1-butanol, respectively, were tested. Overall, all types of yeast applications inhibited undesirable bacterial growth despite salt reduction. Of the starter cultures tested, the mixed culture resulted in a balance of more complex and richer flavors with an identical flavor profile pattern to that obtained from high salt soy sauce. Hence, this strategy using functional yeast cultures offers a technological option to manufacture salt-reduced soy sauce while preserving its typical sensory characteristics without affecting safety. [ABSTRACT FROM AUTHOR]

Abstract: Several yeasts were isolated from Campbell Early grapes (Vitis labrusca cultivar Campbell Early), the major grape cultivar in Korea, grown in two different regions. PCR-RFLP analysis of the ITS I-5.8S-ITS II region showed that 34 isolates out of a total of 40 were in the same group. Phylogenetic analysis revealed that the major strain belonged to one species, Hanseniaspora uvarum, although they displayed some nucleotide mismatches between them. During spontaneous alcohol fermentation at 20 °C, the two grape musts containing 24 °Brix sugar exhibited similar fermentation patterns with differences in final alcohol production and yeast viable counts. PCR analysis of the yeasts randomly isolated during the fermentation using an intron splice site primer showed changes in yeast flora between 8 and 10 days of fermentation. We found that the dominant yeasts displaying various PCR patterns using the primer remained the same throughout the early stages of fermentation, as determined by molecular typing of their ITS regions using PCR-RFLP, and these yeasts were identical to those isolated from grape berries. Among the isolates, the strain designated SS6 was selected based on its potassium metabisulfite resistance, alcohol production (distillation method), and flavor (by sniffing test) of grape juice. When Campbell Early grape must was inoculated with H. uvarum SS6 cells, no differences in fermentation pattern were observed compared with that inoculated with cells of Saccharomyces cerevisiae W-3, an industrial wine yeast strain. However, SS6 wine showed higher levels of organic acid (especially lactic acid), aldehydes, and minor alcohols (except n-propyl alcohol), as well as a higher score in sensory evaluation, compared to those of W-3 wine. [Copyright &y& Elsevier]

Realizing the importance of xylitol as a high-valued compound that serves as a sugar substitute, a new, one step thin layer chromatographic procedure for quick, reliable, and efficient determination of xylose and xylitol from their mixture was developed. Two hundred and twenty microorganisms from the laboratory stock cultures were screened for their ability to produce xylitol from D-xylose. Amongst these, an indigenous yeast isolate no.139 (SM-139) was selected and identified as Debaryomyces hansenii on the basis of morphological and biochemical characteristics and (26S) D1/D2 r DNA region sequencing. Debaryomyces hansenii produced 9.33 gL−1 of xylitol in presence of 50.0 gL−1 of xylose in 84 h at pH 5.5, 30°C, 200 rpm. In order to utilize even higher concentrations of xylose for maximum xylitol production, a xylose enrichment technique was developed. The strain of Debaryomyces hansenii was obtained through xylose enrichment technique in a statistically optimized medium containing 0.3% yeast extract, 0.2% peptone, 0.03% MgSO4.7H2O along with 1% methanol. The culture was inoculated with 6% inoculum and incubated at 30°C and 250 rpm. A yield of 0.6 gg−1 was obtained with a xylitol volumetric productivity of 0.65 g/L h−1 in the presence of 200 gL−1 of xylose although up to 300 gL−1 of xylose could be tolerated through batch fermentation. Through this technique, even higher concentrations of xylose as substrate could be potentially utilized for maximum xylitol production. © 2012 American Institute of Chemical Engineers Biotechnol. Prog., 2012 [ABSTRACT FROM AUTHOR]

To improve wine taste and flavor stability, a novel indigenous strain of Saccharomyces cerevisiae with enhanced glycerol and glutathione (GSH) production for winemaking was constructed. ALD6 encoding an aldehyde dehydrogenases of the indigenous yeast was replaced by a GPD1 and CUP1 gene cassette, which are responsible for NAD-dependent glycerol-3-phosphatase dehydrogenase and copper resistance, respectively. Furthermore, the α-acetohydroxyacid synthase gene ILV2 of the indigenous yeast was disrupted by integration of the GSH1 gene which encodes γ-glutamylcysteine synthetase and the CUP1 gene cassette. The fermentation capacity of the recombinant was similar to that of the wild-type strain, with an increase of 21 and 19 % in glycerol and GSH production. No heterologous DNA was harbored in the recombinant in this study. [ABSTRACT FROM AUTHOR]

Eighteen yeast species belonging to seven genera were isolated from ten samples of nectar from Hibiscus rosa sinensis and investigated for xylitol production using d-xylose as sole carbon source. Amongst these isolates, no. 10 was selected as the best xylitol producer and identified as Candida tropicalis on the basis of morphological, biochemical and 26S rDNA sequencing. C. tropicalis produced 12.11 gl of xylitol in presence of 50 gl of xylose in 72 h at pH 5, 30°C and 200 rpm. The strain of C. tropicalis obtained through xylose enrichment technique has resulted in a yield of 0.5 gg with a xylitol volumetric productivity of 1.07 glh in the presence of 300 gl of xylose through batch fermentation. This organism has been reported for the first time from Hibiscus rosa sinensis flowers. Realizing, the importance of this high valued compound, as a sugar substitute, xylose enrichment technique was developed in order to utilize even higher concentrations of xylose as substrate for maximum xylitol production. [ABSTRACT FROM AUTHOR]

Background and Aims: Winemakers are constantly searching for new techniques to modulate wine style. Exploiting indigenous yeasts present in grape must is re-emerging as a commercial option in New World wine regions. Wines made with indigenous or ‘wild’ yeasts are perceived to be more complex by showing a greater diversity of flavours; however, the chemical basis for the flavour characteristics is not yet defined. In order to evaluate techniques for making wine with the ‘wild yeast fermentation’ character more reliably, it is necessary to define the salient chemical characteristics of such wines. Methods and Results: Pairs of Chardonnay wines were prepared from the same must and subjected to similar fermentation conditions in the wineries of origin, except for the mode of inoculation. Reference wines were made by inoculation with a Saccharomyces cerevisiae starter culture, whereas companion wines were allowed to undergo fermentation with the indigenous microflora. Of all wine chemicals analysed, only yeast-derived volatile fermentation products showed significant differences between the yeast treatments. Conclusions: Inoculated wines were associated with the esters ethyl hexanoate and 3-methylbutyl acetate and formed a clear cluster by principal component analysis. By comparison with inoculated wines, ‘wild’ yeast fermented wines showed high variability in volatile compounds that contribute to wine aroma, with higher concentrations of 2-methylpropanol, 2-methylbutanoic acid, ethyl 2-methylpropanoate, ethyl decanoate and ethyl dodecanoate potentially being sensorially important. Significance of the Study: This study shows that yeast-derived volatile fermentation products are a key difference between inoculated and uninoculated ferments and provides a chemical basis for the ‘wild yeast fermentation’ character. [ABSTRACT FROM AUTHOR]

Brazil is one of the largest ethanol biofuel producers and exporters in the world and its production has increased steadily during the last three decades. The increasing efficiency of Brazilian ethanol plants has been evident due to the many technological contributions. As far as yeast is concerned, few publications are available regarding the industrial fermentation processes in Brazil. The present paper reports on a yeast selection program performed during the last 12 years aimed at selecting Saccharomyces cerevisiae strains suitable for fermentation of sugar cane substrates (cane juice and molasses) with cell recycle, as it is conducted in Brazilian bioethanol plants. As a result, some evidence is presented showing the positive impact of selected yeast strains in increasing ethanol yield and reducing production costs, due to their higher fermentation performance (high ethanol yield, reduced glycerol and foam formation, maintenance of high viability during recycling and very high implantation capability into industrial fermenters). Results also suggest that the great yeast biodiversity found in distillery environments could be an important source of strains. This is because during yeast cell recycling, selective pressure (an adaptive evolution) is imposed on cells, leading to strains with higher tolerance to the stressful conditions of the industrial fermentation. [ABSTRACT FROM AUTHOR]

The production of aroma compounds during tequila fermentation using four native yeast strains isolated from agave juice was quantified at controlled (35 °C) and uncontrolled temperatures (room temperature) by gas chromatography (FID). Three of the four strains were identified as Saccharomyces cerevisiae (MTLI 1, MALI 1 and MGLI 1) and one as Kloeckera apiculata (MALI 2). Among the aroma compounds produced, acetaldehyde has the highest accumulation at the controlled temperature and before 50% of sugar was consumed. The S. cerevisiae strains produced ethyl acetate in almost the same quantity at a concentration of 5 mg/L and the K. apiculata produced six-times more (30 mg/L) than the S. cerevisiae strains, independent of the fermentation temperature. The rate and amount of 1-propanol, amyl alcohols and isobutanol production were affected by the type of yeast used. The K. apiculate strain produced 50% less of the higher alcohols than the Saccharomyces strains. The results obtained showed that indigenous isolated yeasts play an important role in the tequila flavor and suggest that mixtures of these yeasts may be used to produce tequila with a unique and desirable aroma. [ABSTRACT FROM AUTHOR]

Aims: To analyse the genetic diversity and the dynamics of Saccharomyces strains in spontaneous fermentation in ciders. The effect of the cellar, harvest and cider-making technology were evaluated. Methods and Results: The ecology of spontaneous cider fermentations in the same cellar (Asturias) was studied for two consecutive harvests (2000 and 2001) by using mtDNA restriction analysis. Our results showed that there was a succession of genetically different strains of Saccharomyces during cider production. In general, strains of Saccharomyces bayanus species predominated at the early fermentation steps (begining and/or tumultuous fermentations), while Saccharomyces cerevisiae yeasts were the most abundant at the end of the fermentation. Five S. bayanus strains (patterns III, VII, VIII, XV and XVII) were present at significant frequencies in all the experimental tanks during the two consecutive years. The results of the cluster analysis (unweighted pair group method using average linkage) showed higher similarities for the patterns III, XV, VII and VIII. Therefore, these strains should be considered associated with the microbiota of this cellar. Conclusions: A high polymorphism within populations of Saccharomyces was found throughout the different stages of Asturian production of cider. In all the cider fermentations, a variable number of S. bayanus and S. cerevisiae strains was always present. Our results indicate, over the period of time studied, the existence of the natural microbiota in the cellar. Significance and Impact of the Study: This study has allowed us to gain a better understanding of the role of wild Saccharomyces yeast in Asturian cider fermentations. [ABSTRACT FROM AUTHOR]

In Brazil, the process of ethanol production is well established and there are many factors that may contribute to its efficiency, such as the quality of raw material, process conditions and levels of microbial contamination. During industrial fermentations, the microbial population can be quite dynamic, being able to be totally replaced by wild yeasts of low fermentative efficiency. Thus, the present study aimed to evaluate the fermentative characteristics of a flocculent yeast prevalent in the ethanol production process and the implications of this yeast in the kinetic parameters of the process. A wild yeast strain with a contamination level of 77.4% was found within the colonies isolated from the fermented wine. Fermentative tests were carried out with synthetic sugar cane must with 149 gL-1 of ART with this wild flocculent strain (LFS) and its interaction with the industrial strains Saccharomyces cerevisiae BG-1, CAT-1, FT-858L and PE -2. LFS showed a lower performance in productivity and fermentative efficiency compared to industrial strains. In mixed culture fermentative assays with LFS and the BG-1, CAT-1, FT-858L and PE-2 strains, industrial yeasts showed dominance over wild yeast presenting lower levels of final contamination than initial. However, in the mixed culture assays with PE-2 and LFS with addition of calcium oxide in the must, there were concerning results of fermentative efficiency and productivity, since the LFS yeast started to have a higher dominance than what was previously observed. • Wild yeast strain showed lower performance in productivity and fermentative efficiency compared to industrial yeast strains. • The competence of industrial yeast strains reduced contaminant concentrations in mixed cultured fermentations. • Mixed culture fermentations with PE-2 and wild yeast with addition of calcium oxide in the must show results of low efficiency and low fermentative productivity. [ABSTRACT FROM AUTHOR]