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Foods (Basel, Switzerland) Aug 2023Exploitation of the biodiversity of native wine yeast is a means of modifying the sensory characteristics of wine. Samples from different regions in China were analysed...
Exploitation of the biodiversity of native wine yeast is a means of modifying the sensory characteristics of wine. Samples from different regions in China were analysed to screen native isolates as potential starter cultures. Through morphological and molecular biological analyses, we found six species, belonging to four genera (, , and ). These species were subjected to stress tolerance assays (ethanol, glucose, SO and pH), enzymatic activity tests (sulphite reductase activity, β-glucosidase activity and protease activity) and fermentation tests. showed a high tolerance to ethanol and completed fermentation independently. demonstrated good enzymatic activity and completed sequential fermentation. The fermentation experiment showed that the PCT4 strain had the best aroma complexity. This study provides a reference for selecting new starters from the perspective of flavour enzymes and tolerance and diversifying the sensory quality of wines from the region.
PubMed: 37628071
DOI: 10.3390/foods12163073 -
Journal of Fungi (Basel, Switzerland) Jul 2023causes a "milky disease" in Chinese mitten crab, , which inflicts significant damage on the breeding industry, but there are no effective drugs for this disease....
causes a "milky disease" in Chinese mitten crab, , which inflicts significant damage on the breeding industry, but there are no effective drugs for this disease. Precise detection technologies and clarification of transmission routes are now essential to prevent its occurrence. A real-time fluorescent quantitative PCR (qPCR) detection method targeting the mitochondrial cytochrome c oxidase subunit VIA (COX6A) of was developed and its sensitivity, specificity, repeatability, and application effectiveness evaluated. There was a robust linear relationship between the qPCR threshold cycle value (Ct) and copy number of the standard with a wide dynamic range. The standard curve had a correlation coefficient (R) of 0.996, amplification efficiency of 103.092%, and a lower limit of detection sensitivity of 7.6 × 10 copies/µL. The COX6A-qPCR method exhibited high specificity for the detection of , with no cross-reactivity. The intra- and inter-group variation coefficients were <1% and 2%, respectively. The qPCR exhibited superior sensitivity compared to existing detection methods, with a positivity rate of 76.67%. The content ranged from 1.0 × 10-2.7 × 10 copies/µL. The COX6A-qPCR detection technology exhibited high sensitivity, strong specificity, and excellent repeatability, enabling the accurate quantification of .
PubMed: 37623562
DOI: 10.3390/jof9080791 -
BioRxiv : the Preprint Server For... Jul 2023Eukaryotic life depends on the functional elements encoded by both the nuclear genome and organellar genomes, such as those contained within the mitochondria. The...
Eukaryotic life depends on the functional elements encoded by both the nuclear genome and organellar genomes, such as those contained within the mitochondria. The content, size, and structure of the mitochondrial genome varies across organisms with potentially large implications for phenotypic variance and resulting evolutionary trajectories. Among yeasts in the subphylum Saccharomycotina, extensive differences have been observed in various species relative to the model yeast , but mitochondrial genome sampling across many groups has been scarce, even as hundreds of nuclear genomes have become available. By extracting mitochondrial assemblies from existing short-read genome sequence datasets, we have greatly expanded both the number of available genomes and the coverage across sparsely sampled clades. Comparison of 353 yeast mitochondrial genomes revealed that, while size and GC content were fairly consistent across species, those in the genera and trended larger, while several species in the order Saccharomycetales, which includes , exhibited lower GC content. Extreme examples for both size and GC content were scattered throughout the subphylum. All mitochondrial genomes shared a core set of protein-coding genes for Complexes III, IV, and V, but they varied in the presence or absence of mitochondrially-encoded canonical Complex I genes. We traced the loss of Complex I genes to a major event in the ancestor of the orders Saccharomycetales and Saccharomycodales, but we also observed several independent losses in the orders Phaffomycetales, Pichiales, and Dipodascales. In contrast to prior hypotheses based on smaller-scale datasets, comparison of evolutionary rates in protein-coding genes showed no bias towards elevated rates among aerobically fermenting (Crabtree/Warburg-positive) yeasts. Mitochondrial introns were widely distributed, but they were highly enriched in some groups. The majority of mitochondrial introns were poorly conserved within groups, but several were shared within groups, between groups, and even across taxonomic orders, which is consistent with horizontal gene transfer, likely involving homing endonucleases acting as selfish elements. As the number of available fungal nuclear genomes continues to expand, the methods described here to retrieve mitochondrial genome sequences from these datasets will prove invaluable to ensuring that studies of fungal mitochondrial genomes keep pace with their nuclear counterparts.
PubMed: 37577532
DOI: 10.1101/2023.07.28.551029 -
Food Microbiology Oct 2023One interesting strategy to address the increasing alcohol content of wines, associated with climate change, is to reduce the ethanol yield during fermentation. Within...
One interesting strategy to address the increasing alcohol content of wines, associated with climate change, is to reduce the ethanol yield during fermentation. Within this strategy, the approach that would allow the clearest reduction in alcohol content is the respiration of part of the grape sugars by yeasts. Non-Saccharomyces species can be used for this purpose but suffer from a limited ability to dominate the process and complete fermentation. In turn, Saccharomyces cerevisiae shows a high production of acetic acid under the growth conditions required for respiration. Previously proposed procedures used combinations of non-Saccharomyces and S. cerevisiae starters, or a strain of S. cerevisiae (PR1018), with unique metabolic properties. In both cases, precise management of oxygen availability was required to overcome the acetic acid problem. In this work, we have developed a laboratory scale process to take advantage of the properties of PR1018 and a strain of Metschnikowia pulcherrima. This process is more robust than the previous ones and does not rely on strict control of oxygenation or even the use of this particular strain of S. cerevisiae. Aeration can be interrupted instantly without impairing the volatile acidity. Under the selected conditions, an ethanol reduction of around 3% (v/v) was obtained compared to the standard fermentation control.
Topics: Saccharomyces cerevisiae; Wine; Ethanol; Fermentation; Acetic Acid; Vitis
PubMed: 37567627
DOI: 10.1016/j.fm.2023.104344 -
Ecology and Evolution Aug 2023While vertebrate immune systems are appreciated for their complexity and adaptability, invertebrate immunity is often considered to be less complex. However, immune...
While vertebrate immune systems are appreciated for their complexity and adaptability, invertebrate immunity is often considered to be less complex. However, immune responses in many invertebrates likely involve sophisticated processes. Interactions between the crustacean host and its fungal pathogen provide an excellent model for exploring the mechanisms underlying crustacean immunity. To explore the genomic basis of immunity in , we used RNA-sequencing technology to quantify differential gene expression between individuals of a single host genotype exposed or unexposed to over 24 h. Transcriptomic analyses showed that the number of differentially expressed genes between the control (unexposed) and experimental (exposed) groups increased over time. Gene ontology enrichment analysis revealed that differentially expressed genes were enriched for immune-related molecules and processes, such as cuticle development, prostaglandin, and defense response processes. Our findings provide a suite of immunologically relevant genes and suggest the presence of a rapidly upregulated immune response involving the cuticle in . Studies involving gene expression responses to pathogen exposure shine a light on the processes occurring during the course of infection. By leveraging knowledge on the genetic basis for immunity, immune mechanisms can be more thoroughly understood to refine our understanding of disease spread within invertebrate populations.
PubMed: 37529587
DOI: 10.1002/ece3.10354 -
Molecules (Basel, Switzerland) Jun 2023Candidiasis is one of the most frequent infections worldwide. In this study, the antimicrobial properties of six strains belonging to the clade were evaluated against...
Candidiasis is one of the most frequent infections worldwide. In this study, the antimicrobial properties of six strains belonging to the clade were evaluated against twenty and -related var. (syn. ) of different origins, employing the agar cross method. The toxic effect of pulcherrimin, a red metabolite that is responsible for the antimicrobial activities of spp., was evaluated in various experimental models. The results of agar tests showed that the selected strains inhibited the growth of the and non- strains. However, inhibition was dependent on the strain and the environment. The presence of peptone, sodium silicate, and a higher incubation temperature decreased the antifungal action of the strains. Pulcherrimin showed cytotoxic and antiproliferative activity, with oxidative stress in cells leading to apoptosis. More research is needed on the mechanism of action of pulcherrimin on somatic cells.
Topics: Candida; Metschnikowia; Agar; Antifungal Agents; Anti-Infective Agents
PubMed: 37446724
DOI: 10.3390/molecules28135064 -
FEMS Microbiology Ecology Jul 2023Bee-fungus associations are common, and while most studies focus on entomopathogens, emerging evidence suggests that bees associate with a variety of symbiotic fungi... (Review)
Review
Bee-fungus associations are common, and while most studies focus on entomopathogens, emerging evidence suggests that bees associate with a variety of symbiotic fungi that can influence bee behavior and health. Here, we review nonpathogenic fungal taxa associated with different bee species and bee-related habitats. We synthesize results of studies examining fungal effects on bee behavior, development, survival, and fitness. We find that fungal communities differ across habitats, with some groups restricted mostly to flowers (Metschnikowia), while others are present almost exclusively in stored provisions (Zygosaccharomyces). Starmerella yeasts are found in multiple habitats in association with many bee species. Bee species differ widely in the abundance and identity of fungi hosted. Functional studies suggest that yeasts affect bee foraging, development, and pathogen interactions, though few bee and fungal taxa have been examined in this context. Rarely, fungi are obligately beneficial symbionts of bees, whereas most are facultative bee associates with unknown or ecologically contextual effects. Fungicides can reduce fungal abundance and alter fungal communities associated with bees, potentially disrupting bee-fungi associations. We recommend that future study focus on fungi associated with non-honeybee species and examine multiple bee life stages to document fungal composition, abundance, and mechanistic effects on bees.
Topics: Bees; Animals; Fungicides, Industrial; Ecosystem; Mycobiome; Porifera; Metschnikowia; Fungi
PubMed: 37422442
DOI: 10.1093/femsec/fiad077 -
Toxins Jun 2023is a major aflatoxin B, posing significant health concerns to humans, crops, and producer fungi. Due to the undesirable consequences of the usage of synthetic...
is a major aflatoxin B, posing significant health concerns to humans, crops, and producer fungi. Due to the undesirable consequences of the usage of synthetic fungicides, biological control using yeasts has gained more attention. In this study, eight isolates of epiphytic yeasts belonging to sp., sp. and sp., which have been identified as antagonists, were isolated from different plants, including grapes, blueberries, hawthorns, hoşkıran, beans and grape leaf. While volatile organic compounds (VOCs) produced by DN-FY, aff. DN-MP and aff. 32-AMM reduced in vitro mycelial growth and sporulation, only VOCs produced by aff. 1-UDM were found to be effective at reducing in vitro AFB production. All yeasts reduced the mycelial growth of by 76-91%, while AFB production reduced to 1.26-10.15 ng/g and the control plates' growth was 1773 ng/g. The most effective yeast, aff. DN-HS, reduced growth and aflatoxin B production on hazelnuts. The AFB content on hazelnuts reduced to 333.01 ng/g from 536.74 ng/g. To our knowledge, this is the first report of yeasts isolated from plants being tested as potential biological control agents to reduce AFB production on hazelnuts.
Topics: Humans; Aflatoxin B1; Yeasts; Aspergillus; Fungi; Aspergillus flavus; Metschnikowia; Vitis
PubMed: 37368702
DOI: 10.3390/toxins15060402 -
Frontiers in Microbiology 2023The use of non- yeasts as starters in winemaking has increased exponentially in the last years. For instance, non-conventional yeasts have proven useful for the...
The use of non- yeasts as starters in winemaking has increased exponentially in the last years. For instance, non-conventional yeasts have proven useful for the improvement of the organoleptic profile and biocontrol. Active dry yeast starter production has been optimized for , which may entail problems for the propagation of non- yeasts. This work shows that the poor growth of and in molasses is related to a deficient sucrose consumption, linked to their low invertase activity. In order to address this issue, simple modifications to the cultivation media based hydrolysis and the reduction of sucrose concentration were performed. We performed biomass propagation simulations at a bench-top and bioreactor scale. The results show that cultivation in a hexose-based media improved biomass production in both species, as it solves their low invertase activity. The reduction in sugar concentration promoted a metabolic shift to a respiratory metabolism, which allowed a higher biomass yield, but did not improve total biomass production, due to the lower sugar availability. To evaluate the technological performance of these adaptations, we performed mixed grape juice fermentations with biomass produced in such conditions of and The analysis of wines produced revealed that the different treatments we have tested did not have any negative impact on wine quality, further proving their applicability at an industrial level for the improvement of biomass production.
PubMed: 37346752
DOI: 10.3389/fmicb.2023.1209940 -
Microorganisms Apr 2023Drinking wine is a processed beverage that offers high nutritional and health benefits. It is produced from grape must, which undergoes fermentation by yeasts (and... (Review)
Review
Drinking wine is a processed beverage that offers high nutritional and health benefits. It is produced from grape must, which undergoes fermentation by yeasts (and sometimes lactic acid bacteria) to create a product that is highly appreciated by consumers worldwide. However, if only one type of yeast, specifically , was used in the fermentation process, the resulting wine would lack aroma and flavor and may be rejected by consumers. To produce wine with a desirable taste and aroma, non- yeasts are necessary. These yeasts contribute volatile aromatic compounds that significantly impact the wine's final taste. They promote the release of primary aromatic compounds through a sequential hydrolysis mechanism involving several glycosidases unique to these yeasts. This review will discuss the unique characteristics of these yeasts (, , , , , , , , and others) and their impact on wine fermentations and co-fermentations. Their existence and the metabolites they produce enhance the complexity of wine flavor, resulting in a more enjoyable drinking experience.
PubMed: 37317152
DOI: 10.3390/microorganisms11051178