Polyphasic taxonomy of microbacterium soli US15, a novel xylan-degrading bacterium isolated from the soil in Ulsan, Korea

Abstract

A novel xylan-degrading bacterium $US15^T$ was isolated from soil near Ulsan metallic treatement plant. The strain was Gram-positive, non-motile, non-spore-forming and coccoid-shaped rod. It formed yellow colonies on nutrient agar and showed chemotaxonomic markers that were consistent with classification in the genus Microbacterium, i.e. MK-12, MK-11 and MK-13 as major menaquinones; predominating iso- and anteiso-branched cellular fatty acids; glucose, galactose, fucose and mannose as cell-wall sugars; peptidoglycan-type B2β with glycolyl residues; G+C content of 66.5 %. Phylogenetic analysis, based on 16S rRNA gene sequencing, showed strain $US15^T$ was most similar to M. imperiale (96.9%), M. arborescens (96.8%) and M. ulmi (96.2%). It is clear from phylogenetic analyses based on complete 16S rRNA sequences data that the isolate is a member of genus Microbacterium and represents a differentiated phyletic line that can be equated to a separate genomic species. On the basis of these genotypic and phenotypic results, it is proposed that $US15^T ( = DSM 16915^T = KCTC 19080^T)$ be classified as the type strain of a novel Microbacterium species, for which the names Microbacterium soli sp. nov. is proposed.