Microbacterium candidum sp. nov. and Microbacterium capsulatum sp. nov., isolated from waste landfill

Two Gram- stain- positive, oxidase- negative, non- motile and rod- shaped strains (ASV49T and ASV81T) were isolated from a waste landfill in Shanghai, China. Phylogenetic analysis based on 16S rRNA gene sequences indicated that the two strains are associated with members of the genus Microbacterium. Strains ASV49T and ASV81T were most closely related to Microbacterium rhizosphaerae JCM 31396T and Microbacterium bovistercoris CCTCC AA 2018025T with 98.5 and 98.0% 16S rRNA gene sequence similarities, respectively. The genomic DNA G+C contents of strains ASV49T and ASV81T were 69.5 and 70.5 mol %, respectively. Strains ASV49T and ASV81T exhibited the highest average nucleotide identity values of 81.7 and 85.3% against their closest relatives Microbacterium xylanilyticum JCM 13591T and M. rhizosphaerae JCM 31396T, respectively. Corresponding digital DNA- DNA hybridization values were 25.1 and 30.9%, respectively. Strains ASV49T and ASV81T grew optimally at pH 7.0 and 28 degrees C on Reasoner's 2A. Strain ASV81T produced capsules, but ASV49T did not. Both isolates shared the following chemotaxonomic characteristics in common: the major fatty acids of anteiso- C15:0, iso-C16: 0 and anteiso- C17:0; the respiratory quinones of MK- 11, MK- 12, MK- 13 and MK- 10; the polar lipids of diphosphatidylglycerol and phosphatidylglycerol; and the cell wall amino acids of ornithine, alanine, glycine and glutamic acid. Based on the genomic, phenotypic and chemical characteristics, strains ASV49T and ASV81T represent two novel species of the genus Microbacterium, for which the names Microbacterium candidum sp. nov. and Microbacterium capsulatum sp. nov. are proposed. The type strains are ASV49T (=GDMCC 1.4109T=JCM 36480T) and ASV81T (=GDMCC 1.4110T=JCM 36481T), respectively.