Debaryomyces singareniensis sp. nov., a novel yeast species isolated from a coal mine soil in India.

Three strains (AP19, AP19-4 and AP19-6) of a novel yeast species were isolated from soil from the Singareni coal mines, Andhra Pradesh, India. They were morphologically, physiologically and phylogenetically identical and produced one to four spherical ascospores per ascus. Phylogenetic analysis using the D1/D2 variable domain of the large-subunit rRNA gene indicated that the closest relative of these strains is Debaryomyces etchellsii (2.6% divergence). Other species related to these strains are D. mycophilus (5.1% divergence) and species of the D. hansenii cluster (4.9-5.6% divergence). The novel species differs by 20 and 15 physiological tests from D. etchellsii and D. mycophilus, respectively. Phylogenetic analysis of the internal transcribed spacer (ITS) region also indicated that strains of the new species are related to D. etchellsii (7.7% divergence), followed by species of the D. hansenii cluster (9-10% divergence). In the small-subunit rRNA gene sequences, they differed from D. etchellsii by seven substitutions and one insertion or deletion of a base in a sequence (indel) and from D. mycophilus by 17 substitutions and 1 indel. The physiological, biochemical and molecular data suggest that these strains belong to a novel species, for which we propose the name Debaryomyces singareniensis sp. nov. The type strain of AP19(T) (=MTCC 7061(T)=CBS 10405(T)). The Mycobank number of the new species is MB510046.