Proposal of Zygosaccharomyces parabailii sp. nov. and Zygosaccharomyces pseudobailii sp. nov., novel species closely related to Zygosaccharomyces bailii.

Twenty-three yeast strains traditionally identified as Zygosaccharomyces bailii were studied in order to clarify their taxonomy and phylogenetic relationships. The molecular phylogeny from rRNA gene sequences showed that these yeasts were well divided into three major groups, and two of the groups could be clearly distinguished from the type strain of Z. bailii at the species level. Therefore, we propose Zygosaccharomyces parabailii sp. nov. (type strain ATCC 56075(T)  = NBRC 1047(T)  = NCYC 128(T)  = CBS 12809(T)) and Zygosaccharomyces pseudobailii sp. nov. (type strain ATCC 56074(T)  = NBRC 0488(T)  = CBS 2856(T)) to accommodate the yeasts belonging to the two groups. By conventional physiological tests, Z. bailii and the two novel species are not clearly distinguished from one another, as variations exist more frequently between individual strains and are not species-specific. However, the conclusions from rRNA gene sequence analyses are well supported by genome fingerprinting patterns as well as other protein-coding gene sequence comparisons.