[Molecular divergence of the soil yeasts Williopsis sensu stricto].

Fifty-three strains of saturn-spored yeasts were analyzed by means of restriction analysis of the amplified fragment of rDNA which comprised the 5.8S rRNA gene and the internal transcribed spacers ITS1 and ITS2. The use of endonucleases HaeIII and MspI enabled clear differentiation of yeast species Williopsis mucosa, W. salicorniae, Zygowilliopsis californica, Komagataea pratensis, and the Williopsis sensu stricto complex. Minisatellite primer M13 was proposed for the differentiation between twin species of Williopsis sensu stricto, which have identical restriction profiles. PCR with primer M13 enabled reidentification of a number of collection strains, species identification of saturn-spored isolates from the Far East, and detection of three strains affiliated to novel taxa. The latter have unique PCR profiles and differ in the nucleotide sequences of ITS1 and ITS2 fragments of rDNA. Possible variations in the results obtained with different molecular methods are discussed.