Microbacterium hydrothermale sp. nov., an actinobacterium isolated from hydrothermal sediment

A Gram-stain-positive, aerobic, non-motile, rod-shaped bacterium, strain 0704C9-2(T), was isolated from hydrothermal sediment of the Indian Ocean. The organism grew with 0-5% (w/v) NaCl and at 10-37 °C, with optimal growth occurring with 1% NaCl and at 28-30 °C. Comparative 16S rRNA gene sequence analysis revealed that strain 0704C9-2(T) belonged to the genus Microbacterium. It exhibited highest 16S rRNA gene sequence similarity with Microbacterium testaceum DSM 20166(T) (98.4%). Levels of similarity with the type strains of all other recognized species of the genus Microbacterium were less than 98.0%. DNA-DNA hybridization experiments with strain 0704C9-2(T) and its closest relative, M. testaceum DSM 20166(T), revealed a low reassociation value of 42.9%. The DNA G+C content of strain 0704C9-2(T) was 73.3 mol%. The cell-wall peptidoglycan contained ornithine and the acyl type was glycolyl. The major whole-cell sugars were mannose, galactose, rhamnose and glucose. The major cellular fatty acids were anteiso-C15:0, anteiso-C17:0, iso-C16:0 and iso-C15:0. The predominant menaquinones were MK-11, MK-10 and MK-12. The major polar lipids were diphosphatidylglycerol, phosphatidylglycerol, two unknown glycolipids and an unknown phospholipid. On the basis of phenotypic, phylogenetic and genotypic data, strain 0704C9-2(T) represents a novel species within the genus Microbacterium, for which the name Microbacterium hydrothermale sp. nov. is proposed. The type strain is 0704C9-2(T) ( = LMG 27542(T) = CGMCC 1.12512(T)).