Marinobacter fuscus sp. nov., a marine bacterium of Gammaproteobacteria isolated from surface seawater

A Gram-stain-negative bacterium, designated NH169-3 T , was isolated from a surface seawater sample of the South China Sea and subjected to a taxonomic polyphasic investigation. Strain NH169-3 T was strictly aerobic, non-motile, non-spore-forming and rod-shaped. The colony was 1.0-2.0 mm in diameter after the growth on marine agar at 30 °C for 72 h. The centre of the colony was smooth, circular, convex and brown with a transparent periphery. Strain NH169-3 T was able to grow at temperatures between 4-40 °C (optimum, 37 °C), pH 5.5-9.0 (pH 7.5) and with 0-12.5 % (w/v) NaCl (3.0 %). Chemotaxonomic analysis showed that the sole respiratory quinone of strain NH169-3 T was ubiquinone 9; major fatty acids were C16 : 0 and C18 : 1ω9c, and major polar lipids were diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol and one unidentified glycolipid. The DNA G+C content was 52.7 mol%. The comparison of 16S rRNA gene sequences showed that strain NH169-3 T was closely related to Marinobacter shengliensis SL013A34A2 T with a similarity of 98.0 %. Three phylogenetic trees reconstructed with neighbour-joining, maximum-parsimony and maximum-likelihood methods using 16S rRNA gene sequences showed that strain NH169-3 T was grouped into a separated branch with M. shengliensis SL013A34A2 T in a clade of the genus Marinobacter and closely related to Marinobacter halophilus JCM 30472 T , Marinobacter vinifirmus DSM 17747 T and Marinobacter hydrocarbonoclasticus DSM 8798 T . Analyses of both phenotypic and phylogenetic properties have suggested that strain NH169-3 T was distinctive from species with validly published names in genus Marinobacter. Thus, strain NH169-3 T (=MCCC 1K03455 T =KCTC 62226 T ) is proposed as a novel species in genus Marinobacter with the name Marinobacter fuscus sp. nov.