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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 -
Oecologia Feb 2024Invasive species can have large effects on native communities. When native and invasive species share parasites, an epidemic in a native species could facilitate or...
Invasive species can have large effects on native communities. When native and invasive species share parasites, an epidemic in a native species could facilitate or inhibit the invasion. We sought to understand how the incidence and timing of epidemics in native species caused by a generalist parasite influenced the success and impact of an invasive species. We focused on North American native and invasive species of zooplankton (Daphnia dentifera and Daphnia lumholtzi, respectively), that can both become infected with a fungal parasite (Metschnikowia bicuspidata). In a laboratory microcosm experiment, we exposed the native species to varying parasite inocula (none, low, high) and two invasive species introduction times (before or during an epidemic in the native species). We found that the invasive species density in treatments with the parasite was higher compared to uninfected treatments, though only the early invasion, low-parasite and uninfected treatments exhibited significant pairwise differences. However, invasive resting eggs were only found in the uninfected treatments. The density of the native species was lowest with a combination of the parasite present, and the invasive species introduced during the epidemic. Native infection prevalence in these treatments (late invasion, parasite present) was also higher than prevalence in treatments where the invasive species was introduced before the epidemic. Therefore, the timing of an invasion relative to an epidemic can affect both the native and invasive species. Our results suggest that the occurrence and timing of epidemics in native species can influence the impacts of a species invasion.
Topics: Animals; Daphnia; Introduced Species; Zooplankton
PubMed: 37620681
DOI: 10.1007/s00442-023-05444-4 -
Intraspecific variation in realized dispersal probability and host quality shape nectar microbiomes.The New Phytologist Nov 2023Epiphytic microbes frequently affect plant phenotype and fitness, but their effects depend on microbe abundance and community composition. Filtering by plant traits and...
Epiphytic microbes frequently affect plant phenotype and fitness, but their effects depend on microbe abundance and community composition. Filtering by plant traits and deterministic dispersal-mediated processes can affect microbiome assembly, yet their relative contribution to predictable variation in microbiome is poorly understood. We compared the effects of host-plant filtering and dispersal on nectar microbiome presence, abundance, and composition. We inoculated representative bacteria and yeast into 30 plants across four phenotypically distinct cultivars of Epilobium canum. We compared the growth of inoculated communities to openly visited flowers from a subset of the same plants. There was clear evidence of host selection when we inoculated flowers with synthetic communities. However, plants with the highest microbial densities when inoculated did not have the highest microbial densities when openly visited. Instead, plants predictably varied in the presence of bacteria, which was correlated with pollen receipt and floral traits, suggesting a role for deterministic dispersal. These findings suggest that host filtering could drive plant microbiome assembly in tissues where species pools are large and dispersal is high. However, deterministic differences in microbial dispersal to hosts may be equally or more important when microbes rely on an animal vector, dispersal is low, or arrival order is important.
Topics: Animals; Plant Nectar; Pollination; Flowers; Plants; Microbiota; Saccharomyces cerevisiae; Bacteria
PubMed: 37614102
DOI: 10.1111/nph.19195 -
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 2023Considering the growing interest in non-Saccharomyces wine yeasts, and notably in the context of mixed fermentations with S. cerevisiae, understanding their nutritional...
Considering the growing interest in non-Saccharomyces wine yeasts, and notably in the context of mixed fermentations with S. cerevisiae, understanding their nutritional behaviors is essential to ensure better management of these fermentations. The vitaminic consumption of three non-Saccharomyces yeasts (Starmerella bacillaris, Metschnikowia pulcherrima and Torulaspora delbrueckii) was investigated during their growth in wine-like conditions, providing initial evidence that they consume different vitamers. The vitamin consumption profiles during their growth highlighted releases of certain vitamers by the yeasts before re-assimilation, strongly suggesting the existence of synthesis pathways. Not only did the essential character of vitamin B1, in particular, appear to be a trait common to these yeasts, since all its vitamers are consumed, this investigation also provided evidence of the existence of species-dependent preferences for their vitaminic sources. These different behaviors were quite striking in certain vitamers, as was observed in nicotinamide: while it was consumed by T. delbrueckii, it was left untouched by S. bacillaris and produced by M. pulcherrima during growth. Furthermore, this offers grounds for further investigation into these yeasts' requirements, and provides the first tool for managing vitamin resources during mixed fermentations with S. cerevisiae, and for preventing nutritive deficiencies from occurring.
PubMed: 37567637
DOI: 10.1016/j.fm.2023.104332 -
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 -
Archives of Microbiology Aug 2023Recently, there has been growing interest in the characterization of native yeasts for their use in production of wines with regional characteristics. This study aimed...
Recently, there has been growing interest in the characterization of native yeasts for their use in production of wines with regional characteristics. This study aimed to investigate Saccharomyces and non-Saccharomyces yeasts present in the spontaneous fermentation of Tannat and Marselan grape musts collected from Concordia (Entre Ríos, Argentina) over 2019, 2020, and 2021 vintages. The evolution of these fermentative processes was carried out by measuring total soluble solids, total acidity, volatile acidity, pH, ethanol concentration, and total carbon content. Isolated Saccharomyces and non-Saccharomyces yeasts were identified based on colony morphology in WL medium, 5.8S-ITS-RFLP analysis, and 26S rDNA D1/D2 gene sequencing. Two hundred and ten yeast colonies were isolated and identified as Pichia kudriavzevii, Saccharomyces cerevisiae, Hanseniaspora uvarum, Metschnikowia pulcherrima, Candida albicans, Candida parapsilosis, Pichia occidentalis, Pichia bruneiensis, Hanseniaspora opuntiae, Issatchenkia terricola, and Hanseniaspora vineae. P. kudriavzevii isolated from all vintages was associated with the spontaneous fermentation of grape musts from the Concordia region.
Topics: Vitis; Fermentation; Yeasts; Wine; Saccharomyces cerevisiae; DNA, Ribosomal
PubMed: 37550458
DOI: 10.1007/s00203-023-03646-1 -
International Journal of Systematic and... Aug 2023The gut of xylophagous insects such as termites harbours various symbiotic micro-organisms, including many yeast species. In a taxonomic study of gut-associated yeasts,...
The gut of xylophagous insects such as termites harbours various symbiotic micro-organisms, including many yeast species. In a taxonomic study of gut-associated yeasts, two strains (ATS2.16 and ATS2.18) were isolated from the gut of the wood-feeding termite sp. in Maharashtra, India. Morphological and physiological characteristics and sequence analyses of the ITS and D1/D2 region of the large subunit rRNA gene revealed that these two strains represent a novel asexual ascomycetous yeast species in the genus . The species differs from some of its close affiliates in the genus in its inability to utilize ethanol and succinate as the sole carbon source and growth in high sugar concentrations (up to 50 % glucose). In contrast to most members of , the formation of ascospores was not observed on various sporulation media. Moreover, whole-genome sequencing was used to further confirm the novelty of this species. When compared with other large-spored species, average nucleotide identity values of 79-80 % and digital DNA-DNA hybridization values of 16-17 % were obtained. The name f.a., sp. nov. is proposed to accommodate this novel yeast species, with ATS2.16 as the holotype and strains NFCCI 4949, MTCC 13085 and PYCC 9152 as isotypes. The MycoBank number is MB 844210.
Topics: Animals; Metschnikowia; Isoptera; Wood; Phylogeny; Sequence Analysis, DNA; India; RNA, Ribosomal, 16S; DNA, Bacterial; Bacterial Typing Techniques; Base Composition; Fatty Acids; Yeasts; Porifera; DNA, Fungal; DNA, Ribosomal Spacer; Mycological Typing Techniques; Saccharomycetales
PubMed: 37540005
DOI: 10.1099/ijsem.0.006012 -
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