Three yeast strains, DMKU-MP6-4T, DMKU-MP2-6 and DMKU-MP5-1, were isolated from the small-intestinal content or Pia of cattle in Thailand during the investigation of yeast diversity in this habitat. According to the D1/D2 domain of the large subunit (LSU) rRNA gene and internal transcribed spacer (ITS) region sequence analysis, these strains represent a novel yeast species in the genus Pichia. The species produced one to four ascospores per ascus with spherical to ellipsoidal shape and heterogenous in terms of size. These three strains were identical and differed from their closely related species, Pichia exigua NRRL Y-10920T by 2% (six nucleotide substitutions and five gaps) in the D1/D2 domain of the large subunit rRNA gene, while ITS region sequences differed by 3.1% (16 nucleotide substitutions and 27 gaps), 3.7% (19 nucleotide substitutions and 28 gaps) and 3.1% (16 nucleotide substitutions and 27 gaps) for DMKU-MP6-4T, DMKU-MP2-6 and DMKU-MP5-1, respectively. The name, Pichia bovicola, is proposed to accommodate these species. The holotype is DMKU-MP6-4T (TBRC 15616T=PYCC 8905T).
Keywords: Pia; Pichia bovicola; Thailand; novel yeast species.