Use of RAPD and mitochondrial DNA RFLP for typing of Candida zeylanoides and Debaryomyces hansenii yeast strains isolated from cheese

In order to evaluate the genetic diversity of the yeast flora in Northern Spain cheese, we adapted two molecular techniques devised for Saccharomyces, RAPD and RFLP of mitochondrial DNA, to type 27 Candida zeylanoides strains and 28 Debaryomyces hansenii strains isolated from Roncal and Idiazabal cheese at different stages of manufacture in different dairies. RAPD with (GTG)(5) primer, although very reproducible, only defined 2 groups of strains for both species. On the other hand, mtDNA RFLP proved to be more discriminating and defined 5 groups pf strains for both species. In addition, the strains from the minor RAPD groups in both species corresponded to specific groups defined by mtDNA RFLP. Overall, this analysis has revealed an important genetic diversity, considering the limited sample of different biotopes tested. Nevertheless, the mt DNA RFLP results indicate that a large majority of the strains appeared closely related, suggesting little variability between cheese and dairies. This work has demonstrated that rapid identification methods (the typing of strains can be achieved in two days) can be applied to these poorly characterized yeast species, allowing a rapid evaluation of genetic diversity of these species in different biotopes.