Microbacterium xylanilyticum sp. nov., a xylan-degrading bacterium isolated from a biofilm

Abstract

A novel xylan-degrading bacterium, S3-ET, was isolated from the biofilm of a membrane bioreactor. The cells of this strain were Gram-positive, non-motile, non-spore-forming rods, produced primary branches and formed yellow colonies on nutrient agar. The strain had chemotaxonomic markers that were consistent with classification in the genus Microbacterium, i.e. MK-12, MK-11 and MK-13 as the major menaquinones, predominant iso- and anteiso-branched cellular fatty acids, glucose and galactose as the cell-wall sugars, peptidoglycan-type B2β with glycolyl residues and a DNA G+C content of 69·7 mol%. Phylogenetic analysis, based on 16S rRNA gene sequencing, showed that strain S3-ET is most similar to Microbacterium hominis IFO 15708T and Microbacterium foliorum DSM 12966T (97·6 and 97·4 % sequence similarity, respectively), and that it forms a separate lineage with M. hominis in the genus Microbacterium. DNA–DNA hybridization results and phenotypic properties showed that strain S3-ET could be distinguished from all known Microbacterium species and represented a novel species, for which the name Microbacterium xylanilyticum sp. nov. is proposed; the type strain is S3-ET (=DSM 16914T=KCTC 19079T).