Academic literature on the topic 'Yeast culture heterogeneity'

Malassezia is a lipid-dependent commensal yeast of the human skin. The different culture media and skin sampling methods used to grow these fastidious yeasts are a source of heterogeneity in culture-based epidemiological study results. This study aimed to compare the performances of three methods of skin sampling, and two culture media for the detection of Malassezia yeasts by culture from the human skin. Three skin sampling methods, namely sterile gauze, dry swab, and TranswabTM with transport medium, were applied on 10 healthy volunteers at 5 distinct body sites. Each sample was further inoculated onto either the novel FastFung medium or the reference Dixon agar for the detection of Malassezia spp. by culture. At least one colony of Malassezia spp. grew on 93/300 (31%) of the cultures, corresponding to 150 samplings. The positive culture rate was 67%, 18%, and 15% (P < 10−3), for samples collected with sterile gauze, TranswabTM, and dry swab, respectively. The positive culture rate was 62% and 38% (P < 0.003) by using the FastFung and the Dixon media, respectively. Our results showed that sterile gauze rubbing skin sampling followed by inoculation on FastFung medium should be implemented in the routine clinical laboratory procedure for Malassezia spp. cultivation.

The use of yeast starter cultures consisting of a blend of Saccharomyces cerevisiae and non-Saccharomyces yeasts has increased in recent years as a mean to address consumers’ demands for diversified wines. However, this strategy is currently limited by the lack of a comprehensive knowledge regarding the factors that determine the balance between the yeast-yeast interactions and their responses triggered in complex environments. Our previous studies demonstrated that the strain Hanseniaspora guilliermondii UTAD222 has potential to be used as an adjunct of S. cerevisiae in the wine industry due to its positive impact on the fruity and floral character of wines. To rationalize the use of this yeast consortium, this study aims to understand the influence of production factors such as sugar and nitrogen levels, fermentation temperature, and the level of co-inoculation of H. guilliermondii UTAD222 in shaping fermentation and wine composition. For that purpose, a Central Composite experimental Design was applied to investigate the combined effects of the four factors on fermentation parameters and metabolites produced. The patterns of variation of the response variables were analyzed using machine learning methods, to describe their clustered behavior and model the evolution of each cluster depending on the experimental conditions. The innovative data analysis methodology adopted goes beyond the traditional univariate approach, being able to incorporate the modularity, heterogeneity, and hierarchy inherent to metabolic systems. In this line, this study provides preliminary data and insights, enabling the development of innovative strategies to increase the aromatic and fermentative potential of H. guilliermondii UTAD222 by modulating temperature and the availability of nitrogen and/or sugars in the medium. Furthermore, the strategy followed gathered knowledge to guide the rational development of mixed blends that can be used to obtain a particular wine style, as a function of fermentation conditions.

ABSTRACT Indigenous yeast population dynamics during the fermentation of healthy and Botrytis-affected grape juice samples from two regions in Greece, Attica and Arcadia, were surveyed. Species diversity was evaluated by using restriction fragment length polymorphism and sequence analyses of the 5.8S internal transcribed spacer and the D1/D2 ribosomal DNA (rDNA) regions of cultivable yeasts. Community-level profiles were also obtained by direct analysis of fermenting samples through denaturing gradient gel electrophoresis of 26S rDNA amplicons. Both approaches revealed structural divergences in yeast communities between samples of different sanitary states or geographical origins. In all cases, Botrytis infection severely perturbed the bioprocess of fermentation by dramatically altering species heterogeneity and succession during the time course. At the beginning and middle of fermentations, Botrytis-affected samples possessed higher levels of biodiversity than their healthy counterparts, being enriched with fermentative and/or spoilage species, such as Zygosaccharomyces bailii and Issatchenkia spp. or Kluyveromyces dobzhanskii and Kazachstania sp. populations that have not been reported before for wine fermentations. Importantly, Botrytis-affected samples exposed discrete final species dominance. Selection was not species specific, and two different populations, i.e., Saccharomyces cerevisiae in samples from Arcadia and Z. bailii in samples from Attica, could be recovered at the end of Botrytis-affected fermentations. The governing of wine fermentations by Z. bailii is reported for the first time and could elucidate the origins and role of this particular spoilage microbe for the wine industry. This is the first survey to compare healthy and Botrytis-affected spontaneous fermentations by using both culture-based and -independent molecular methods in an attempt to further illuminate the complex yeast ecology of grape must fermentations.

New technologies have powered rapid advances in cellular imaging, genomics and phenotypic analysis in life sciences. However, most of these methods operate at sample population levels and provide statistical averages of aggregated data that fail to capture single-cell heterogeneity, complicating drug discovery and development. Here we demonstrate a new single-cell approach based on convex lens-induced confinement (CLiC) microscopy. We validated CLiC on yeast cells, demonstrating subcellular localization with an enhanced signal-to-noise and fluorescent signal detection sensitivity compared with traditional imaging. In the live-cell CLiC assay, cellular proliferation times were consistent with flask culture. Using methotrexate, we provide drug response data showing a fivefold cell size increase following drug exposure. Taken together, CLiC enables high-quality imaging of single-cell drug response and proliferation for extended observation periods.

ABSTRACT Infections with the human pathogenic basidiomycetous yeastCryptococcus neoformans are often treated with fluconazole. Resistance to this antifungal agent has been reported. This study investigated the patterns of mutation to fluconazole resistance inC. neoformans in vitro. The MIC of fluconazole was measured for 21 strains of C. neoformans. The MICs for these 21 strains differed (0.25 to 4.0 μg/ml), but the strains were selected for this study because they exhibited no growth on plates of yeast morphology agar (YMA) containing 8 μg of fluconazole per ml. To determine their mutation rates, six independent cultures from a single original colony were established for each of the 21 strains. Each culture was then spread densely on a YMA plate with 8 μg of fluconazole per ml. A random set of putative mutants was subcultured, and the MIC of fluconazole was determined for each mutant. The 21 strains evinced significant heterogeneity in their mutation rates. The MICs of the putative mutants ranged widely, from their original MIC to 64 μg of fluconazole per ml. However, for this set of 21 strains, there was no significant correlation between the original MIC for a strain and the mutation rate of that strain; the MIC for the mutant could not be predicted from the original MIC. These results suggest that dynamic and heterogeneous mutational processes are involved in generating fluconazole resistance in C. neoformans.

Background: Cryptococcus is encapsulated opportunistic yeast that causes life threatening meningoencephalitis of patients with human immunodeficiency virus (HIV). The magnitude of Cryptococcosis among HIV patients varies from 1-10% in Western countries as opposed to almost a one third of HIV-infected individuals in sub-Saharan Africa where it is associated with high mortality. Methodology: By using key terms “Cryptococcosis among HIV patients in sub-saharan Africa countries”, articles that published in different journals from 2010-2017 searched on Pub-Med and Google scholar database. Those freely accessible and included the prevalence of Cryptococcosis in the result section, their PDF file was downloaded and the result extracted manually and presented in table. Articles that did not report the prevalence of Cryptococcosis, with a study design otherthan cross sectional, or a sample size less than 100, and those duplicated in the same study area and period by the same authors were excluded. The article selec- tion followed the PRISMA guidelines and meta- analysis was performed using OpenMeta(analyst). Results: The overall pooled magnitude of Cryptococcosis among HIV patients in sub saharan African countries was 8.3% (95%CI 6.1-10.5%). The highest prevalence was from Uganda (19%) and the least was from Ethiopia at 1.6%. There was 87.2 % of substantial heterogeneity among the studies with p-value<0.001. The symmetry ofthe forest plot showed that there was little publication bias. The most commonly used method for diagnosis of Cryptococcosis was lateral flow assay and latex agglutination test and culture was the least method employed. Conclusion: The overall pooled magnitude of Cryptococcosisis high among HIV patients in sub-Saharan African countries. The studies showed substantial heterogeneity, and little publication bias. Most of the studies relied on LFA & LA that showed the scarcity of facilities for fungal culture. Therefore, paying attention to screening HIV patients; those with signs and symptoms of meningitis may help to reduce the loss of HIV patients. Keywords: Cryptococcosis; sub-Saharan African; HIV; meta-analysis.

Abstract Most intracellular proteins are expressed with their interacting ligands. If a protein shows restricted normal tissue expression, its interacting ligand will likely also follow a restricted normal tissue expression pattern. We hypothesized that protein molecules interacting with CT antigens may also be testicular restricted and potential CT antigens. Identification of these proteins provides the opportunity for their application in polyvalent tumor vaccines to overcome the problems associated with antigen heterogeneity within a tumor specimen. We have applied two known CT antigens, Sperm protein 17 (Sp17) and SEMG1, as baits in yeast two-hybrid systems of a testicular cDNA library to identify the protein interacting with these two antigens and determine whether the interacting protein are also CT antigens. To do so, we first isolated and amplified cDNA encoding Sp17 and SEMG1. Following successful amplification and sequence confirmation, the cDNAs were sub-cloned into pGBKT7 and transformed into yeast strain AH109 and selected on SD/-Trp plates. Mating was performed between AH109-pGBKT7-Sp17 or pGBKT7-SEMG 1 and pre-transformed human testis cDNA library in yeast strain Y187. Following mating, the culture was first selected on SD/-His/-Leu/-Trp plates and then on SD/-Ade/-His/-Leu/-Trp/X-a -Gal plates. A total of 17 positive clones were isolated using Sp17 and 24 positive clones using SEMG 1 as the bait. Following confirmation of interaction, the colonies were expanded and the the plasmids subjected to sequence identification by nucleotide analysis. All 17 clones isolated using Sp17 encoded Ropporin 1 and all 24 clones isolated using SEMG 1 encoded Protamine 1. Using RT-PCR on total RNA derived from a panel of normal tissues, we demonstrated the very restriction normal tissue expression of Protamine 1 and Ropporin 1, being present only in normal testis, indicating that they are also testicular-specific genes. Analysis of a panel of fresh tumor cells, we showed the aberrant expression of both Protamine 1 and Ropporin 1 in a proportion of hematologic malignancies, including acute myeloid leukemia, multiple myeloma and chronic lymphocytic leukemia, supporting the notion that Ropporin 1 and Protamine 1 are both novel CT antigens in hematologic malignancies. Furthermore, these antigens were also able to elicit high titer B-cell responses in vivo in these patients, suggesting their immunogenicity in the autologous host, even in cancer-bearing patients. Interestingly, the expression of one partner CT antigen within an individual tumor specimen does not necessary predict for the co-expression of the interacting CT antigen. In conclusion, we have described a novel approach to the identification of CT antigens that could be used for immune targeting. This approach could be applied using other known CT antigens to identify other tumor antigens. The lack of a good correlation between the expressions of the partner protein with the interacting protein suggests two important points. First, the aberrant expression of these interacting pair of molecules is not a result of coordinated intracellular regulatory mechanisms but likely due to random processes. Second, if the function of one protein is dependent on the presence of its ligand, then these individual molecules expressed within the tumor cells are unlikely to be of any functional significance in the tumor cells from most patients.

Microbiological reports of apical periodontitis have revealed that yeasts can be isolated from approximately 5-20% of infected root canals. They occur either in pure cultures or together with bacteria. Almost all isolated yeasts belong to the genus Candida, and the predominant species is C. albicans. Pheno- and genotypic profiles of C. albicans isolates show heterogeneity comparable with those of isolates from other oral sites. C. albicans expresses several virulence factors that are capable of infecting the dentin-pulp complex, including dentinal tubules. This causes, consequentially, an inflammatory response around the root apex, which suggests a pathogenic role for this organism in apical periodontitis. Yeasts are particularly associated with persistent root canal infections that do not respond favorably to conservative root canal therapy. This may be due to the resistance of all oral Candida species against a commonly used topical medicament, calcium hydroxide. However, other antimicrobial agents may offer alternative therapeutic approaches and improve the treatment of these persistent cases of apical periodontitis.

The spatial organization of the nucleus is a key determinant in all genome activities. However, the accurate measurement of the nuclear organization is still technically challenging. Here, the technology NucQuant we created previously was utilized to detect the variation of the nuclear organization, including the heterogeneity of the nuclear geometry, the change of the NPC distribution along different cell cycle stages during interphase, and the organization of the nucleolus. The results confirmed that not only the growth rate and the NPC distribution are influenced by the carbon source; the nuclear shape is also impacted by the carbon source. The nuclei lost their spherical geometry gradually when the cell was cultured from the most to a less favorable carbon source. We also discovered that the nucleolus prefers to locate at the nuclear periphery, which was called the “genes poor region,” especially when the cells entered quiescence. Furthermore, the distribution of the NPC along the different stages during the interphase was analyzed. We proposed that with the growth of the cell, the nucleus would grow from the surface of the NE flanking the nucleolus firstly.