Phenotypic and genotypic characterization of probiotic yeasts

Abstract

Yeast classification is traditionally based on their physiological and biochemical profiles. However, molecular methods have been recently successfully applied to yeast strain typing and identification. The aim of this research was to characterize probiotic yeast strains by classical (morphology, reproduction, biochemical features) and molecular (karyotype analysis) methods. Nine strains of Saccharomyces boulardii were examined: two strains from ATCC Collection and seven probiotic strains isolated from medicines. Although there were some variations in biochemical utilization of carbon and nitrogen compounds, all the strains were identified as Saccharomyces cerevisiae according to their morphological characteristics and assimilation profiles. Chromosomal patterns of yeasts consisted of 13–14 bands ranging from 222 to 2251 kb, what indicated their classification to the genus S. cerevisiae. According to current nomenclature the tested yeasts should be referred as S. cerevisiae var. boulardii. © 2009 Taylor and Francis Group, LLC.