Studies on the heterogeneity of the carotenogenic yeast Rhodotorula mucilaginosa from Patagonia, Argentina

LIBKIND FRATI, D; GADANHO, M; VAN BROOCK, MR; SAMPAIO, JP

Slovenia

Congreso; 1st FEMS Congress; 2003

The basidiomycetous red yeast Rhodotorula mucilaginosa is a ubiquitous species and can be found both in natural and in human-related environments. Due mostly to similar physiological profiles, several species are presently regarded as synonyms of Rh. mucilaginosa, although very few have been investigated using molecular methods. In this study, forty five Rh. mucilaginosa isolates obtained from diverse natural and artificial environments (lakes, soil, nectar, wild fruits, grape surfaces) from Patagonia, Argentina, were studied. The methods employed encompassed morphological and physiological characterisations, DNA fingerprinting using MSP-PCR (mini/micro-satellite primed-PCR), single nucleotide sequencing (SNS) and DNA sequence analysis of the D1/D2 and ITS regions. Preliminary MSP-PCR experiments using primer (GTG)5 revealed considerable heterogeneity in Rh. mucilaginosa. When primer M13 was employed, three subgroups were formed, one of them encompassing the type strain and 84% of the strains studied. Physiological and morphological results also correlated with the presence of the three groups. No sexual compatibility reactions were observed between or within these groups. Selected isolates were investigated by sequence analysis. In contrast with the D1/D2 region, the less conserved ITS region revealed differences between the tested strains of the different groups. However, no correlations were found between the three groups and the geographic origin of the isolates or their isolation source. The observed heterogeneity is presently interpreted as intraspecific variability. Future work will expand the set of studied isolates, will address the molecular relationships of the current synonyms of Rh. mucilaginosa and will conceivably allow a better understanding of the heterogeneity presently reported.