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New Candida species such as Candida auris have emerged recently as important invasive fungal diseases. We report a case of C. bovina bloodstream infection in a 94-year-old patient in France. The species led to identification issues because it was misidentified by phenotypic and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry methods.

Kefir—a traditional beverage whose consumption has been associated with health benefits—is a logical natural product to investigate for new probiotic strains. The aim of the present work was to isolate and identify kefir yeasts and select those with acid and bile tolerance to study their adhesion to epithelial cells and their transit through mouse gut. From 4 milky and 3 sugary kefir grains, 34 yeast strains were isolated and identified by means of classical microbiological and molecular-genetic methods (whole-cell protein pattern, internal-transcribed-spacer amplification, and analysis of restriction-fragment–length polymorphisms). We identified 4 species belonging to 3 genera—Saccharomyces cerevisiae (15 strains), Saccharomyces unisporus (6 strains), Issatchenkia occidentalis (4 strains), and Kluyveromyces marxianus (9 strains)—and selected 13 strains on the basis of resistance to low pH and bile salts. Among the strains selected, Kluyveromyces marxianus CIDCA 8154 and Saccharomyces cerevisiae CIDCA 8112 were further studied. Both strains evidenced the capacity to adhere to epithelial intestine-derived cells in vitro and to survive passage through the gastrointestinal tract of BALB/c mice. The investigation of the potential probiotic features of these kefir-yeast strains should be useful for the development of novel functional foods.

ABSTRACT Budding yeasts are distributed across a wide range of habitats, including as human commensals. However, under some conditions, these commensals can cause superficial, invasive, and even lethal infections. Despite their importance to human health, little is known about the ecology of these opportunistic pathogens, aside from their associations with mammals and clinical environments. During a survey of approximately 1000 non-clinical samples across the United States of America, we isolated 54 strains of budding yeast species considered opportunistic pathogens, including Candida albicans and Candida (Nakaseomyces) glabrata. We found that, as a group, pathogenic yeasts were positively associated with fruits and soil environments, whereas the species Pichia kudriavzevii (syn. Candida krusei syn. Issatchenkia orientalis) had a significant association with plants. Of the four species that cause 95% of candidiasis, we found a positive association with soil. These results suggest that pathogenic yeast ecology is more complex and diverse than is currently appreciated and raises the possibility that these additional environments could be a point of contact for human infections. Here we describe the isolation of more than 50 strains of budding yeast opportunistic pathogens from natural settings, suggesting that they have more complex ecology than is currently appreciated.

Prevalence of emerging fungal infections is increasing, particularly among immunocompromised persons, children, and older persons. We report 108 cases of Scheffersomyces spartinae infection in pediatric patients from Karachi and other cities in Pakistan, of which 107 were identified from blood cultures. Cultures were initially misidentified as Clavispora lusitaniae by a biochemical assay before speciation as S. spartinae by whole-genome sequencing. All isolates were from children <12 years of age, and >69% were from children <1 month of age. Isolates were genetically distinct across regions of Pakistan; however, genetic diversity was low in isolates from patients in Karachi and nearby Nawabshah and had median differences of just 9 pairwise nucleotide variants. This study demonstrates S. spartinae is a potentially emerging pathogen in neonates and young infants in Pakistan. The findings highlight the limitations of phenotypic identification for detecting emerging fungal infections and underscore the value of molecular identification approaches.

Mango is affected by different decline disorders causing significant losses to mango growers. In the United Arab Emirates (UAE), the pathogen was isolated from all tissues sampled from diseased trees affected by Lasiodiplodia theobromae. Symptoms at early stages of the disease included general wilting appearance of mango trees, and dieback of twigs. In advanced stages, the disease symptoms were also characterized by the curling and drying of leaves, leading to complete defoliation of the tree and discolouration of vascular regions of the stems and branches. To substantially reduce the devastating impact of dieback disease on mango, the fungus was first identified based on its morphological and cultural characteristics. Target regions of 5.8S rRNA (ITS) and elongation factor 1-α (EF1-α) genes of the pathogen were amplified and sequenced. We also found that the systemic chemical fungicides, Score®, Cidely® Top, and Penthiopyrad®, significantly inhibited the mycelial growth of L. theobromae both in vitro and in the greenhouse. Cidely® Top proved to be a highly effective fungicide against L. theobromae dieback disease also under field conditions. Altogether, the morphology of the fruiting structures, molecular identification and pathogenicity tests confirm that the causal agent of the mango dieback disease in the UAE is L. theobromae.

Ethanol content of wine has increased over the last decades as consequence of searching phenolic maturity, requiring increased grape maturity. This may result in the production of wines with excessive alcohol levels (sometimes more than 15% (v/v)), sluggish and stuck fermentations and excessive volatile acidity. Many strategies to reduce ethanol in wines are being studied, and microbial methods have some additional advantages. However, because of the broad intra- and interspecies variability, new selection criteria should be included. Therefore, the goal of the present work was to design and evaluate a simple and integral procedure for non-Saccharomyces yeast selection. This strategy allowed selection of yeasts that presented successful implantation in grape must with high alcohol potential and their use in co-cultures could reduce the ethanol in wines. A total of 114 native non-Saccharomyces yeasts were assayed to determine their respiratory, fermentative and physiological characteristics of enological interest. Hanseniaspora uvarum BHu9 and BHu11, H. osmophila BHo51, Starmerella bacillaris BSb55 and Candida membranaefaciens BCm71 were selected as candidates to design co-culture starters.

Microfungi that inhabit floral nectar offer unique opportunities for the study of microbial distribution and the role that dispersal limitation may play in generating distribution patterns. Flowers are well-replicated habitat islands, among which the microbes disperse via pollinators. This metapopulation system allows for investigation of microbial distribution at multiple spatial scales. We examined the distribution of the yeast, Metschnikowia reukaufii, and other fungal species found in the floral nectar of the sticky monkey flower, Mimulus aurantiacus, a hummingbird-pollinated shrub, at a California site. We found that the frequency of nectar-inhabiting microfungi on a given host plant was not significantly correlated with light availability, nectar volume, or the percent cover of M aurantiacus around the plant, but was significantly correlated with the location of the host plant and loosely correlated with the density of flowers on the plant. These results suggest that dispersal limitation caused by spatially nonrandom foraging by pollinators may be a primary factor driving the observed distribution pattern.

Abstract Yeasts are widely distributed in marine ecosystems and play essential roles in maintaining their productivity. However, the identification of yeasts in marine invertebrates, especially in organisms used for human consumption, such as oysters, remains limited. This study aimed to identify yeast species in Crassostrea sp. oysters, collected from wild-harvesting and aquaculture sites along the Amazonian coast of Maranhão, Brazil. A total of 40 oyster samples were collected over two sampling months and subjected to microbiological analysis using Potato Dextrose Agar following serial decimal dilutions. Molecular identification was performed through ITS rRNA sequencing, and species similarity was assessed in dendrograms. Microbiological results revealed the presence of both mycelial fungi and yeasts, with higher densities of mycelial fungi found in the extraction and cultivation areas, whose averages were approximately 1.7 × 103 and 2.1 × 103 CFU/g, respectively, with high variability among samples. Yeasts were more abundant in cultivated oysters (4.3 × 103 CFU/g) compared to wild oysters (6.2 × 102 CFU/g). This study focused exclusively on yeast strains and molecularly identified Meyerozyma guilliermondii and Trichosporon asahii among the isolates. This is the first report of these species in oysters. These yeasts may have an allochthonous origin associated with anthropogenic factors and natural dispersion, as both are frequently found in warm-blooded animals. Therefore, this study provides relevant data for future investigations into the ecological roles of yeasts in marine invertebrates and their impacts on coastal ecosystems. Resumo Leveduras estão amplamente distribuídas no ecossistema marinho e desempenham papéis essenciais na produtividade desse ambiente. No entanto, a identificação de leveduras em invertebrados marinhos, especialmente em organismos utilizados na alimentação humana, como ostras, ainda é escassa. Este estudo tem como objetivo identificar leveduras em ostras Crassostrea sp., coletadas em áreas de extrativismo de moluscos bivalves e de ostreicultura, na costa amazônica maranhense, Brasil. Foram coletadas 40 amostras de ostras no total durante dois meses amostrais e inoculadas para ensaios microbiológicos em meio de Batata-Dextrose-Ágar após diluições em séries decimais. A identificação molecular foi realizada por sequenciamento do rRNA ITS, e a similaridade das espécies foi analisada em dendogramas. Os resultados microbiológicos indicaram a presença de fungos miceliais e leveduras, com maior densidade de fungos miceliais nas áreas de extrativismo e cultivo, cujas médias foram de aproximadamente 1,7 × 103 e 2,1 × 103 UFC/g, respectivamente, e com alta variabilidade entre as amostras. As leveduras apresentaram maior abundância nas áreas de cultivo (4,3 × 103 UFC/g) em comparação às de extrativismo (6,2 × 102 UFC/g). Este estudo focou, exclusivamente, nas cepas de leveduras e identificou molecularmente Meyerozyma guilliermondii e Trichosporon asahii dentre os isolados. Este relato foi pioneiro nessas espécies em ostras. Essas leveduras podem ter origem alóctone associada a fatores antropogênicos e à dispersão natural, pois ambas são, frequentemente, encontradas em animais de sangue quente. Portanto, o presente estudo fornece dados relevantes para futuras investigações sobre os papéis ecológicos das leveduras em invertebrados marinhos e sobre seus impactos em ecossistemas costeiros.

Polyethylene (PE) is a primary contributor to environmental plastic pollution, posing a critical risk to ecosystems and living organisms. This study screened six yeast strains (BI.4.1.1, K3.1.2, M.5.0.1, M.5.0.3, M.6.0.1, and M.6.0.2) isolated from marine plastic debris in East Java, Indonesia, for their ability to degrade PE. Among these, Meyerozyma carpophila M6.0.2 demonstrated functional characteristics with the highest polyethylene-degrading activity in liquid medium after a 10-day incubation, with a degradation percentage of 0.4923%. This was supported by its biofilm-forming capacity, biosurfactant production, and broad metabolic activity as demonstrated by EcoPlate assays. In addition, Scanning Electron Microscope (SEM) and Fourier Transform Infrared Spectroscopy (FTIR) analyses of PE films revealed morphological changes and emergence of new peaks, respectively. Whole-genome sequencing (WGS) of strain M6.0.2 was performed using the Illumina NextSeq 2000 platform (PE 150), yielding a genome assembly of 10.34 Mb across 108 contigs with an N50 length of 1.08 Mb. A total of 5,352 putative genes were predicted. These findings highlight Meyerozyma carpophila M6.0.2 as a promising candidate for bioremediation of marine plastic pollution, emphasizing the combination of functional and genomic insights for a better understanding of the mechanism of PE biodegradation.

Compared to its status as an experimental model system and importance to industry, the ecology and genetic diversity of the genus Saccharomyces has received less attention. To investigate systematically the biogeography, community members and habitat of these important yeasts, we isolated and identified nearly 600 yeast strains using sugar-rich enrichment protocols. Isolates were highly diverse and contained representatives of more than 80 species from over 30 genera, including eight novel species that we describe here: Kwoniella betulae f.a. (yHKS285T = NRRL Y-63732T = CBS 13896T), Kwoniella newhampshirensis f.a. (yHKS256T = NRRL Y-63731T = CBS 13917T), Cryptococcus wisconsinensis (yHKS301T = NRRL Y-63733T = CBS 13895T), Cryptococcus tahquamenonensis (yHAB242T = NRRL Y-63730T = CBS 13897T), Kodamaea meredithiae f.a. (yHAB239T = NRRL Y-63729T = CBS 13899T), Blastobotrys buckinghamii (yHAB196T = NRRL Y-63727T = CBS 13900T), Candida sungouii (yHBJ21T = NRRL Y-63726T = CBS 13907T) and Cyberlindnera culbertsonii f.a. (yHAB218T = NRRL Y-63728T = CBS 13898T), spp. nov. Saccharomyces paradoxus was one of the most frequently isolated species and was represented by three genetically distinct lineages in Wisconsin alone. We found a statistically significant association between Quercus (oak) samples and the isolation of S. paradoxus, as well as several novel associations. Variation in temperature preference was widespread across taxonomic ranks and evolutionary timescales. This survey highlights the genetic and taxonomic diversity of yeasts and suggests that host and temperature preferences are major ecological factors. To better characterize yeast habitats and biodiversity, we isolated nearly 600 yeast strains using sugar-rich enrichment protocols, including more than 80 species, eight of which are new to science.