Characterization of mating type on aroma production and metabolic properties wild Kluyveromyces marxianus yeasts.

Kluyveromyces marxianus yeasts represent a valuable industry alternative due to their biotechnological potential to produce aromatic compounds. 2-phenylethanol and 2-phenylethylacetate are significant aromatic compounds widely used in food and cosmetics due to their pleasant odor. Natural obtention of these compounds increases their value, and because of this, bioprocesses such as de novo synthesis has become of great significance. However, the relationship between aromatic compound production and yeast's genetic diversity has yet to be studied. In the present study, the analysis of the genetic diversity in K. marxianus isolated from the natural fermentation of Agave duranguensis for Mezcal elaboration is presented. The results of strains in a haploid and diploid state added to the direct relationship between the mating type locus MAT with metabolic characteristics are studied. Growth rate, assimilate carbohydrates (glucose, lactose, and chicory inulin), and the production of aromatic compounds such as ethyl acetate, isoamyl acetate, isoamyl alcohol, 2-phenylethyl butyrate and phenylethyl propionate and the diversity in terms of the output of 2-phenylethanol and 2-phenylethylacetate by de novo synthesis were determinate, obtaining maximum concentrations of 51.30 and 60.39 mg/L by ITD0049 and ITD 0136 yeasts respectively.

Identification and susceptibility of clinical isolates of Candida spp. to killer toxins / Identificação e susceptibilidade de isolados clínicos de Candida spp. para toxinas assassinas

Abstract Although invasive infections and mortality caused by Candida species are increasing among compromised patients, resistance to common antifungal agents is also an increasing problem. We analyzed 60 yeasts isolated from patients with invasive candidiasis using a PCR/RFLP strategy based on the internal transcribed spacer (ITS2) region to identify different Candida pathogenic species. PCR analysis was performed from genomic DNA with a primer pair of the ITS2-5.8S rDNA region. PCR-positive samples were characterized by RFLP. Restriction resulted in 23 isolates identified as C. albicans using AlwI, 24 isolates as C. parapsilosis using RsaI, and 13 as C. tropicalis using XmaI. Then, a group of all isolates were evaluated for their susceptibility to a panel of previously described killer yeasts, resulting in 75% being susceptible to at least one killer yeast while the remaining were not inhibited by any strain. C. albicans was the most susceptible group while C. tropicalis had the fewest inhibitions. No species-specific pattern of inhibition was obtained with this panel of killer yeasts. Metschnikowia pulcherrima, Pichia kluyveri and Wickerhamomyces anomalus were the strains that inhibited the most isolates of Candida spp.

Resumo Embora as infecções invasivas e a mortalidade causada por espécies de Candida estejam aumentando entre pacientes comprometidos, a resistência a agentes antifúngicos comuns também é um problema crescente. Analisamos 60 leveduras isoladas de pacientes com candidíase invasiva utilizando como estratégia PCR/RFLP baseada na região espaçadora transcrita interna (ITS2) para identificar diferentes espécies patogênicas de Candida. A análise por PCR foi realizada a partir de ADN genómico com um par de iniciadores da região ITS2-5.8S rDNA. As amostras PCR-positivas foram caracterizadas por RFLP. A restrição resultou em 23 isolados identificados como C. albicans usando AlwI, 24 isolados como C. parapsilosis usando RsaI e 13 como C. tropicalis usando XmaI. Em seguida, avaliou-se o grupo de todos os isolados quanto à sua susceptibilidade a um painel de leveduras killer previamente descritas, resultando em 75% sendo suscetíveis a pelo menos uma levedura killer, enquanto que as restantes não foram inibidas por qualquer cepa. C. albicans foi o grupo mais suscetível enquanto C. tropicalis teve o menor número de inibições. Não se obteve um padrão de inibição específico da espécie com este painel de leveduras killer. Metschnikowia pulcherrima, Pichia kluyveri e Wickerhamomyces anomalus foram as cepas que inibiram a maioria dos isolados de Candida spp.

Identification and susceptibility of clinical isolates of Candida spp. to killer toxins.

Although invasive infections and mortality caused by Candida species are increasing among compromised patients, resistance to common antifungal agents is also an increasing problem. We analyzed 60 yeasts isolated from patients with invasive candidiasis using a PCR/RFLP strategy based on the internal transcribed spacer (ITS2) region to identify different Candida pathogenic species. PCR analysis was performed from genomic DNA with a primer pair of the ITS2-5.8S rDNA region. PCR-positive samples were characterized by RFLP. Restriction resulted in 23 isolates identified as C. albicans using AlwI, 24 isolates as C. parapsilosis using RsaI, and 13 as C. tropicalis using XmaI. Then, a group of all isolates were evaluated for their susceptibility to a panel of previously described killer yeasts, resulting in 75% being susceptible to at least one killer yeast while the remaining were not inhibited by any strain. C. albicans was the most susceptible group while C. tropicalis had the fewest inhibitions. No species-specific pattern of inhibition was obtained with this panel of killer yeasts. Metschnikowia pulcherrima, Pichia kluyveri and Wickerhamomyces anomalus were the strains that inhibited the most isolates of Candida spp.

Transcriptomic analysis of basidiocarp development in Ustilago maydis (DC) Cda.

Previously, we demonstrated that when Ustilago maydis (DC) Cda., a phytopathogenic basidiomycete and the causal agent of corn smut, is grown in the vicinity of maize embryogenic calli in a medium supplemented with the herbicide Dicamba, it developed gastroid-like basidiocarps. To elucidate the molecular mechanisms involved in the basidiocarp development by the fungus, we proceeded to analyze the transcriptome of the process, identifying a total of 2002 and 1064 differentially expressed genes at two developmental stages, young and mature basidiocarps, respectively. Function of these genes was analyzed with the use of different databases. MIPS analysis revealed that in the stage of young basidiocarp, among the ca. two thousand differentially expressed genes, there were some previously described for basidiocarp development in other fungal species. Additional elements that operated at this stage included, among others, genes encoding the transcription factors FOXO3, MIG3, PRO1, TEC1, copper and MFS transporters, and cytochromes P450. During mature basidiocarp development, important up-regulated genes included those encoding hydrophobins, laccases, and ferric reductase (FRE/NOX). The demonstration that a mapkk mutant was unable to form basidiocarps, indicated the importance of the MAPK signaling pathway in this developmental process.

Differential expression of serine protease inhibitors 1 and 2 in Crassostrea corteziensis and C. virginica infected with Perkinsus marinus.

Proliferation of Perkinsus marinus (Dermo) in vitro is inhibited by the action of 2 serine protease inhibitors belonging to the I-84 family. We compared the levels of expression of serine protease inhibitors 1 and 2 (SPI-1 and SPI-2) in 2 oyster species (Crassostrea virginica and C. corteziensis) inoculated with the parasite P. marinus. C. virginica is well known to be susceptible to this parasite, whereas C. corteziensis is apparently more tolerant. Oysters were inoculated with trophozoites (1 × 106 trophozoites oyster-1) of P. marinus while control oysters were injected with saline solution. Oysters were maintained in a closed water system for 2 wk. The oysters were then sacrificed and parasite burden, histological damage, and gene expression were evaluated. The results showed that the challenged oysters presented a significant increase in parasite burden, which generated histological damage in digestive gland and gills. Quantitative PCR detected significant differences in SPI-1 and SPI-2 expression levels in the 2 oyster species, with C. corteziensis showing higher expression levels than C. virginica as a response to P. marinus inoculation. Our results provide valuable information for the understanding of the defense response in C. corteziensis and a possible explanation for its tolerance to the parasite.