In our article using sequence analyses of the combined D1/D2 domains of the 26S rDNA (LSU) and the internal transcribed spacer region ITS1+2 (ITS) we demonstrated that the Kazachstania clade does not represent a single stable monophyletic clade with a large number of shared characteristics. Yeast species of the Kazachstania clade, four new Bulgarian strains (IMBBR1, IMBBR2, IMB190, IMB190R) and an outgroup species Kluyveromyces marxianus are split into five clusters. Our results show strong correlation between molecular evolutionary distance (ED) and sequence identity values (SIV). Sequence identity values also correlated with the distances between physiological profiles (DPP). Cut-off values of SI, molecular ED and DPP are proposed for separation of species and genera of the Kazachstania clade. Our results showed that four Bulgarian strains represent two new yeast species of the genus Kazachstania . In addition, a new genus Grigorovia is proposed to transfer four yeast species that previously belonged to the genus Kazachstania .
Key words: cut-off values, molecular evolutionary distance, sequence identity value, yeast physiological profiles, Kazachstania
Topic: BIOLOGY