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-sporeforming and rod-shaped. The colony was 1.0-2.0 mm in diameter after the growth on marine agar at 30 degrees 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 degrees C (optimum, 37 degrees 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 C-16(:0) and C-18(:1)omega 9c, 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 Glade 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.