Mitochondria -: Tool for taxonomic identification of yeasts from Saccharomyces sensu stricto complex

Mitochondrial genomes of Saccharomyces and close relatives previously used for transplacement of mitochondria to S, cerevisiae were examined. The origins of replication in mitochondrial DNA, the presence of nuclear and mitochondrial polymorphic loci and the ability to produce mitochondrial respiration-deficient mutants were used to reclassify some collection yeasts and to assign others into four separate subgroups. The first included isolates identical to Saccharomyces cerevisiae (S. italicus. S. oviformis, S. chevalieri and S. capensis) which possess 5 or more replication origins. The second group consists of S, paradoxus (var. douglasii) mitochondrial genome with the equal number of ori sequences but incompatible mitochondria. The third group represents Saccharomyces sensu stricto petite-positive species (S, carlsbergensis, S. heterogenous, S. uvarum, S. willianus) with 1-2 origins of replication significantly different from S. cerevisiae. In addition, the locus between tRNA(fMet) and tRNA(PRO) is about one-half of the 1400 bp members of S. cerevisiae complex. The last group includes isolates that do not belong to Saccharomyces sensu stricto group as they are petite-negative and devoid of any S. cerevisiae-like replication origins.