SCREENING AND CHARACTERIZATION OF STRESS TOLERANT SACCHAROMYCES CEREVISIAE ISOLATED FROM BREWERY EFFLUENTS FOR ANIMAL PROBIOTIC APPLICATIONS

Based on the colony morphology and microscopic characteristics, 26 yeasts were isolated from different sources including brewery effluents. Initially they were screened for their thermotolerance at 40 0C and only 5 strains were selected. They were later grown in yeast extract peptone dextrose medium to screen their stress tolerance at five different temperatures; at different concentrations of a mixture of acetic, propionic and butyric acids; at different pH; at different concentrations of glucose and bile salts. Based on the growth at different stress conditions, yeast OBV9 was selected and characterized as Saccharomyces cerevisiae by sequencing its 5.8S rRNA gene and internal transcribed spacer (ITS) 1 and 2. The sequence obtained was most similar (99%) to S. cerevisiae, when it was blast searched in NCBI database and showed a separate branch in phylogenetic analysis.