Proteolytic, lipolytic and molecular characterisation of Yarrowia lipolytica isolated from cheese.

This work studied the qualitative and quantitative proteolytic and lipolytic activities of Yarrowia lipolytica strains isolated from two cheese types. Randomly amplified polymorphic DNA-PCR (RAPD-PCR) analysis was used to compare the cheese strains of Y. lipolytica with strains isolated from other food products and with the type strain of the species in order to investigate the genetic diversity and occurrence of specific environmental groups. Diversity of proteolytic and especially lipolytic activity within Y. lipolytica strains isolated from dairy products was observed. In particular, the degree of specificity for saturated or unsaturated fatty acids as well as for even- or odd-numbered carbon free fatty acids (FFAs) varied among the strains. The RAPD-PCR profiles showed low genetic relatedness between many of the food isolates and the type strain of the species. Such genetic variability needs to be further evaluated. Most of the Y. lipolytica strains appeared to be specific to the particular environment from which they were isolated. However, phenotypic characteristics having technological importance in dairy products and, particularly, lipolytic activities did not correspond to the genetic differences observed by RAPD-PCR analysis.