This study aims to characterize the Mel+ strains that was unusual for L. thermotolerans, as well as some Mel- strains isolated in Far East, Finland, and the Crimea.According to the data, a population represented by a type culture and a second, genetically divergent, melibiose-utilizing yeast population belong to this species.There are two genetic groups of Lachancea thermotolerans strains, the first one includes the type strain NRRL Y-8284 and the strains incapable of melibiose utilizing as a rule.The second species consists of melibiose-utilizing strains.Both species are cosmopolitan, because they are encountered in different parts of the world.The population structure of yeast L. thermotolerans represents an interesting model for studying the ecol. genetic mechanisms of inter- and intraspecific differentiation.