Metschnikowia sanitii f.a., sp. nov., a new ascomycetous yeast species isolated from mangrove forests in Thailand

Abstract

Seven strains representing a novel ascomycetous yeast species were isolated from the leaf phylloplane (DMKU-SG60) and the floral surface (DMKU-FF11, DMKU-FF12, DMKU-FD2, DMKU-FD6, DMKU-FS1 and ST-387) of mangrove trees in Thailand. Pairwise sequence analysis indicated that the strains were identical or differed by one to two nucleotide substitution(s) in the D1/D2 domains of the large subunit (LSU) rRNA gene. They also were identical or differed by one to four nucleotide substitution(s) in the internal transcribed spacer (ITS) region. blastn searches of the GenBank database revealed that the closest related species was Metschnikowia rancensis, differing by 28 (5.5-6.0%) and 30-33 (8.0-8.9%) nucleotide substitutions in the D1/D2 domains of the LSU rRNA gene and the ITS region, respectively. Moreover, whole-genome sequencing was used to further confirm the separation of this species. In comparison with other related species, average nucleotide identity values of 74.6-76.5% and digital DNA-DNA hybridization values of 12.8-13.3% were obtained. Phylogenetic analysis based on the concatenated sequences of the ITS region and the D1/D2 domains of the LSU rRNA gene, as well as phylogenomic analysis, showed that these strains belong to the genus Metschnikowia, but at a distinct position relative to other recognized species. Based on molecular analyses and phenotypic characteristics, the strains represent a novel species, for which the name Metschnikowia sanitii f.a., sp. nov. is proposed. The holotype is TBRC 19861T, and the ex-type culture is PYCC 10335 (DMKU-FF11). The MycoBank number is MB 860254.