Microbacterium gubbeenense sp. nov., from the surface of a smear-ripened cheese

Phenotypic and phylogenetic studies were performed on 11 strains of a Microbacterium-like organism isolated from the surface of a smear-ripened cheese. The isolates were Gram-positive, catalase-positive, facultatively anaerobic, oxidase-negative, non-spore-forming, non-motile, small, slender rods and grew in 12% (w/v) NaCl. Chemotaxonomic investigation revealed that all the isolates belonged unambiguously to the genus Microbacterium. They contained type B1 peptidoglycans with L-lysine as the diamino acid and glycolyl acyl types; rhamnose and galactose were the cell wall sugars. The G+C content ranged from 69 to 72 mol%. The major menaquinones were MK-11 and MK-12 and the major fatty acids were anteiso C15:0 and C17:0 and iso C16:0. Phylogenetic analysis of the 16S rRNA sequences of four isolates showed that they represented a new subline in the genus Microbacterium, with Microbacterium barkeri as their nearest phylogenetic neighbour. M. barkeri showed the highest sequence similarity to the isolates; however, DNA-DNA hybridization showed that the isolates had only 38% chromosomal similarity to M. barkeri. Based on the phylogenetic and phenotypic distinctiveness of the isolates, it is proposed that they be classified as a new Microbacterium species, for which the name Microbacterium gubbeenense sp. nov. is suggested. The type strain has been deposited as LMG S-19263T (= NCIMB 30129T). The GenBank accession number for the 16S rDNA sequence of the type strain is AF263563.