ENZYMATIC CHARACTERIZATION OF YEAST STRAINS ORIGINATED FROM TRADITIONAL MIHALIC CHEESE

摘要

Yeasts, associated with secondary flora of many cheese types, are important microorganisms for cheese ripening process. The aim of this study was to identify the yeasts isolated from traditional Mihalic cheese and to determine their enzymatic activities as a tool for their technological characteristics. Phenotypic identification was performed by using API ID 32C test system and some complementary morphological, physiological and biochemical tests. Enzyme profiles of the isolates were determined by using API-ZYM strips. In this study, 72 yeast isolates were obtained from 29 Mihalic cheese samples. Fifty-six (78%) of the isolates could be identified at species level, and one isolate at genus level. The identified yeast species belonged to three genera; Candida, Geotrichum and Trichosporon. It was determined that Candida famata var. famata was the dominant species in Mihalic cheese. The yeast isolates had variable enzyme activities including acid phosphatase, esterase, esterase lipase, lipase, β-galactosidase, leucine arylamidase, valine arylamidase and cysteine arylamidase, which could have important attributes during cheese ripening. C. famata var. famata M22, Candida guilliermondii var. membranefaciens M54 and Candida tropicalis M2 were selected to be superior strains on the basis of their enzyme profiles. Identification and enzymatic characterization of the yeasts originated from Mihalic cheese was performed for the first time in this study.