Modestobacter marinus sp nov., a psychrotolerant actinobacterium from deep-sea sediment, and emended description of the genus Modestobacter

The taxonomic status of an actinobacterium that changed colour during growth, strain 42H12-1(T) isolated from deep-sea sediment collected from the Atlantic Ocean, was established using a combination of genotypic and phenotypic data. Strain 42H12-1(T) formed a distinct branch in the 16SrRNA gene phylogenetic tree together with the type strains in the genus Modestobacter. The highest sequence similarity by BLAST analysis was to Modestobacter versicolor CP153-2(T) (98.5%) and the second-highest sequence similarity was to Modestobacter multiseptatus AA-826(T) (97.5 %). DNA-DNA relatedness of only 12% (SD 1.82%) between strain 42H12-1(T) and M. versicolor DSM 16678(T) differentiated them as members of separate genomic species. Colonies of strain 42H12-1(T) were black on oligotrophic medium, but orange to red, turning black, on copiotrophic medium. The peptidoglycan contained meso-diaminopimelic acid. The polar lipids were diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, phosphatidylinositol and an unknown aminophospholipid. The predominant menaquinone was MK-9(H-4). The major fatty acids were iso-C-16:0 and C-17:1 omega 8c. The DNA G + C content was 72.3 +/- 1 molok. Strain 42H12-1(T) (=DSM 45201(T) =CGMCC 4.5581(T)) is assigned as the type strain of a novel species of the genus Modestobacter, for which the name Modestobacter marinus sp. nov. is proposed.