MOLECULAR IDENTIFICATION AND METABOLIC SCREENING OF SOME YEAST STRAINS FROM FOODS

Abstract

Yeast strains from Saccharomyces, Kluyveromyces and Candida genera are present in most foods representing the basis for various industrial and biotechnological processes. The strains CMGB79 and CMGB159 were identified using PCR-RFLP on the ITS1-5.8S-ITS2 region as belonging to Candida parapsilosis, respectively, to Kluyveromyces marxianus. The primer OPA03 yield the highest degree of intraspecific RAPD polymorphism for the strains Saccharomyces cerevisiae CMGB59, CMGB121and ATCC201583. Lipase production was observed in the presence of Tween 80 in concentration of 0.1 and 0.5% for Candida parapsilosis CMGB79, respectively, 0.1 to 0.8% for Candida parapsilosis CBS604. The oleic acid represented the best substrate for lipase induction and cell growth for Kluyveromyces marxianus CMGB159. All the yeast strains tested positive for lipase synthesis in the presence of tributyrin. The antagonistic interactions between the studied strains were assessed using killer assays against Candida parapsilosis CMGB79 and CBS604. The killer activity was high for Kluyveromyces marxianus CMGB159 and good for the Saccharomyces cerevisiae strains, the toxin representing a stress factor which determined modifications in the sensitive cells. The results obtained during the present work showed that the characterized yeast strains present an important potential for applications in food industry, in obtaining probiotic compounds or as therapeutic agents of biomedical interest.