Abstract
Two novel actinomycetes, designated MN07-A0368(T) and MN07-A0371(T), were isolated from soil of Terelj, Tov Province, Mongolia, and subjected to phenotypic and genotypic characterization. They produced well-developed, non-fragmenting, extensively branched substrate hyphae from which oval to irregular sporangia were produced. Chemotaxonomic characteristics, i.e. cell wall diaminopimelic acid, whole-cell sugars, fatty acid components and major menaquinones, suggested that the two organisms belonged to the genus Actinoplanes. A comparative analysis of 16S rRNA gene sequences indicated that strains MN07-A0368(T) and MN07-A0371(T) formed a distinct clade within the genus and were closely related to the type strains of: Actinoplanes ferrugineus (97.7% sequence similarity); Actinoplanes brasiliensis (97.7-97.8 %); Actinoplanes deccanensis (97.6-97.9 %); Actinoplanes durhamensis (96.9-97.00/o); and Actinoplanes globisporus (96.5-96.8%). Strains MN07-A0368(T) and MN07-A0371(T) could be differentiated from each other and from strains of closely related species of the genus Actinoplanes by DNA-DNA hybridization, physiological and biochemical characteristics, fatty acid composition, and whole-cell sugar components. The broad range of phenotypic and genetic characters supported the suggestion that these strains represent two novel species of the genus Actinoplanes, for which the names Actinoplanes toevensis sp. nov. (type strain MN07-A0368(T)=NBRC 105298(T)=VTCC D9-11(T)) and Actinoplanes tereljensis sp. nov. (type strain MN07-A0371(T) =NBRC 105297(T)=VTCC D9-10(T)) are proposed.