Abstract
Two actinomycetes, designated MN08-A0270(T) and MN08-A0297(T), were isolated from soil from the area around Khuvsgul Lake, Khuvsgul province, Mongolia, and subjected to phenotypic and genotypic characterization. They produced well-developed, branched substrate hyphae and, similar to closely related species of the genus Pseudonocardia, produced zigzag-shaped aerial hyphae by acropetal budding and blastospores. A comparative analysis of 16S rRNA gene sequences indicated that strains MN08-A0270(T) and MN08-A0297(T) formed two distinct clades within the genus Pseudonocardia and were respectively most closely related to Pseudonocardia yunnanensis NBRC 15681(T) (97.3 % similarity) and Pseudonocardia thermophila IMSNU 20112(T) (97.1 %). Chemotaxonomic characteristics, including cell-wall diaminopimelic acid, whole-cell sugars, fatty acid components and major menaquinones, suggested that the two organisms belonged to the genus Pseudonocardia. Strains MN08-A0270(T) and MN08-A0297(T) could be differentiated from each other and from closely related species of the genus Pseudonocardia by physiological and biochemical characteristics, predominant fatty acids, menaquinones and whole-cell sugar components. Combined with the results of a broad range of phenotypic tests and DNA-DNA hybridization data and phylogenetic analysis, these results support the conclusion that these strains represent two novel species of the genus Pseudonocardia, for which we propose the names Pseudonocardia mongoliensis sp. nov. (type strain MN08-A0270(T) = NBRC 105885(T) = VTCC D9-25(T)) and Pseudonocardia khuvsgulensis sp. nov. (type strain MN08-A0297(T) = NBRC 105886(T) = VTCC D9-26(T)).