Chrysosporium-Related Fungi and Reptiles : a Fatal Attraction

10.1371/journal.ppat.100436

Two new lipid-dependent Malassezia species from domestic animals

During a study on the occurrence of lipid-dependent Malassezia spp. in domestic animals, some atypical strains, phylogenetically related to Malassezia sympodialis Simmons et Guého, were shown to represent novel species. In this study, we describe two new taxa, Malassezia caprae sp. nov. (type strain MA383=CBS 10434), isolated mainly from goats, and Malassezia equina sp. nov. (type strain MA146=CBS 9969), isolated mainly from horses, including their morphological and physiological characteristics. The validation of these new taxa is further supported by analysis of the D1/D2 regions of the 26S rRNA gene, the ITS1-5.8S-ITS2 rRNA, the RNA polymerase subunit 1 and chitin synthase nucleotide sequences, and the amplified fragment length polymorphism patterns, which were all consistent in separating these new species from the other species of the genus, and those of the M. sympodialis species cluster, specifically

Quantification of Malassezia pachydermatis by real-time PCR in swabs from the external ear canal of dogs

Financial support for this project came from Servei Veterinari de Bacteriologia i Micologia from the Universitat Autònoma de Barcelona.Malassezia pachydermatis is part of the normal microbiota of canine skin and external ear canal, and is also associated with otitis externa in dogs. Laboratory detection of Malassezia otitis relies on the presence of elevated numbers of the yeast on cytologic examination of otic exudate. Although cytology has high specificity, it has low sensitivity, resulting in false-negatives and posing a challenge for clinicians to accurately diagnose Malassezia otitis. We developed a quantitative PCR (qPCR) to detect and quantify M. pachydermatis yeasts and validate the method with swabs from external ear canals of dogs. Our qPCR uses the β-tubulin gene, a single-copy gene, as a target. The limit of quantification was established as 0.18 ng/reaction, equivalent to 2.0 × 10 genome equivalents (gEq). Swabs from healthy dogs yielded quantification values of ≤2.7 × 10 gEq in the qPCR, whereas swabs from dogs with otitis yielded quantification values of ≥2.5 × 10 gEq. Our qPCR assay provides accurate quantification of M. pachydermatis yeasts from swab samples from dogs, is more sensitive than cytology, and could be used to monitor response to treatment. Our assay could also be valuable in a research setting to better understand the pathogenesis of M. pachydermatis

Black aspergilli and ochratoxin A in foods

Ochratoxin A (OTA) is a potent nephrotoxin and carcinogen which is found in a wide variety of common foods and beverages. The black aspergilli are distributed worldwide and are regarded as common food spoilage fungi. These fungi are one of the more difficult groups concerning classification and identification. New molecular approaches have shown that there is a high biodiversity, but that species are occasionally difficult to recognise based solely on their phenotypic characters. Only few species have been confirmed to be OTA producers in this group and fewer are known to contaminate foods with this mycotoxin as a natural occurring contaminant. In this paper, the OTA-producing species included in the Aspergillus section Nigri and the foods that they are able to contaminate are reviewed in depth

ERG11 Gene Variability and Azole Susceptibility in Malassezia pachydermatis

Malassezia pachydermatis is part of the normal skin microbiota of various animal species but under certain circumstances becomes an opportunistic pathogen producing otitis and dermatitis. Commonly these Malassezia diseases are effectively treated using azoles. However, some cases of treatment failure have been reported. Alterations in the ERG11 gene have been associated with in vitro azole resistance in M. pachydermatis. In the present study, in vitro antifungal susceptibility of 89 different strains of M. pachydermatis isolated from different animal species and health status was studied. The susceptibility to fluconazole (FLZ), itraconazole (ITZ), ketoconazole and amphotericin B was tested by a disk diffusion method and 17 strains were also subjected to an ITZ E-test. Mueller-Hinton supplemented with 2% glucose and methylene blue was used as culture medium in both susceptibility assays. Multilocus sequence typing was performed in 30 selected strains using D1D2, ITS, CHS2 and β-tubulin genes. Also, ERG11 genewas sequenced. The four antifungals tested were highly effective against most of the strains. Only two strains showed no inhibition zone to antifungals and a strain showed an increased MIC to ITZ. The study of the ERG11 sequences revealed a high diversity of DNA sequences and a total of 23 amino acid substitutions, from which only two have been previously described. Also, three deleterious substitutions (A302T, G459D and G461D) previously associated with azole resistance in this yeast were recovered. A correlation between certain genotypes and ERG11 mutations was observed. Some of the ERG11 mutations recovered were correlated with a reduced susceptibility to azoles

Problemàtica de les micotoxines en el vi

Títol del póster : Mycotoxins in wine, are they a problem

Intraspecific variability of growth and ochratoxin A production by Aspergillus carbonarius from different foods and geographical areas

Ochratoxin A (OTA) is a nephrotoxic mycotoxin naturally found in a wide range of food commodities throughout the world. Aspergillus carbonarius is the most important source of OTA in food commodities such as wine, grapes and dried vine fruits and is also responsible for the formation of OTA in coffee. The aim of this study was to determine the simultaneous effect of three culture media (Czapek Yeast Extract Broth (CYB); Synthetic Grape Juice Medium (SGM) and White grape juice (WGJ)) at three water activity (aw) levels (0.90; 0.95 and 0.98-0.99), and three incubation temperatures (15ºC, 25ºC and 35ºC) on the growth and OTA production by 16 strains of A. carbonarius. The strains were selected on the basis of the geographical origin of the substrate and included strains from different climatic zones of Spain as well as from other countries with different climatology. All the strains were confirmed for identity by sequencing of the calmodulin gene. The assay was performed in microtiter plates, determining the absorbance at 530 nm and the concentration of OTA after 1, 2, 4 and 10 days of incubation. No significant differences were observed in absorbance values between the strains. The highest absorbance values were recorded in CYB at 0.99 aw and at 0.95 aw after 10 days of incubation at 25ºC and 35ºC. None of the strains were able to grow at 0.90 aw and 15ºC in any culture media after 10 days of incubation. OTA concentration was statistically higher at 15ºC than at 25ºC or 35ºC. The highest significant OTA values were obtained at 0.98-0.99 aw and the best culture media for OTA production was CYB, followed by WGJ and SGM. While strains isolated from Mediterranean climate foods had a similar behavior despite being isolated from different geographical areas, OTA concentration produced by one Robusta coffee strain from Thailand was statistically higher at 25ºC than at 15ºC. This would suggest that the type of food matrices and consequently the adaptation of A. carbonarius strains to different climatic conditions would have a greater influence on the ecophysiology of the strains than only their geographical origin

Introducció a la Microbiologia

Contingut de les classes de Microbiologia. Primer curs. Grau de Ciencia i Tecnologia dels aliments i Grau de Veterinàri