Oceanomicrobium pacificus gen. nov., sp. nov., a member of the family Rhodobacteraceae isolated from seawater of tropical western Pacific

The Gram-stain-negative, aerobic, ovoid or rod-shaped bacterial strain, designated KN286(T), was isolated from seawater of tropical western Pacific. Growth occurred between 15 and 40 degrees C (optimally at 30-35 degrees C), pH 6-9 (optimally at 7.0) and in the presence of 0.5-5.0% (w/v) NaCl (optimally between 2.0 and 3.0%). Strain KN286(T) contained Q-10 as the major respiratory quinone. The polar lipid profile contained phosphatidylethanolamine, phosphatidylglycerol, phosphatidylcholine, three phospholipids, three glycolipids, and three unidentified polar lipids. The predominant cellular fatty acid was summed feature 8 (composed of C-18:1 omega 7c and/or C-18:1 omega 6c). Phylogenetic analysis of the 16S rRNA gene sequence revealed that strain KN286(T) was a member of the family Rhodobacteraceae and formed a distinct lineage. Strain KN286(T) has a genome size of 3.25 Mbp and a G + C content of 65.0 mol%. It encoded with some genes for carbohydrate-active enzymes, such as GH20 (Glycoside Hydrolase Family 20) and PL1 (Polysaccharide Lyase Family 1) and did not encode with a set of genes for reduction of nitrate to nitrite (nitrate reductase gamma subunit, respiratory nitrate reductase alpha N-terminal and respiratory nitrate reductase beta C-terminal). Based on phylogenetic analyses with single-copy orthologous clusters, low isDDH value (19.6%), low ANI (72.4%) and low AAI (65.7%) results, differential chemotaxonomic and physiological properties, strain KN286(T) represents a novel species of a novel genus of the family Rhodobacteraceae, for which the name Oceanomicrobium pacificus gen. nov., sp. nov. is proposed. The type strain of Oceanomicrobium pacificus is KN286(T) (=CGMCC 1.17118(T) = KCTC 72430(T)).

Automated summary

This study isolated a Gram-stain-negative, aerobic bacterial strain from seawater of tropical western Pacific. The strain showed growth characteristics within a wide range of temperature, pH, and salt concentration, and lacked genes related to nitrate reduction. Phylogenetic analyses identified it as a novel species of a novel genus of the family Rhodobacteraceae, proposed to be named Oceanomicrobium pacificus.