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

Abstract

The taxonomic status of an actinobacterium that changed colour during growth, strain 42H12-1T, isolated from deep-sea sediment collected from the Atlantic Ocean, was established using a combination of genotypic and phenotypic data. Strain 42H12-1T formed a distinct branch in the 16S rRNA gene phylogenetic tree together with the type strains in the genus Modestobacter. The highest sequence similarity by blast analysis was to Modestobacter versicolor CP153-2T (98.5 %) and the second-highest sequence similarity was to Modestobacter multiseptatus AA-826T (97.5 %). DNA–DNA relatedness of only 12 % (sd 1.82 %) between strain 42H12-1T and M. versicolor DSM 16678T differentiated them as members of separate genomic species. Colonies of strain 42H12-1T 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(H4). The major fatty acids were iso-C16 : 0 and C17 : 1ω8c. The DNA G+C content was 72.3±1 mol%. Strain 42H12-1T ( = DSM 45201T  = CGMCC 4.5581T) is assigned as the type strain of a novel species of the genus Modestobacter, for which the name Modestobacter marinus sp. nov. is proposed.