Physiological and genomic features of Paraoceanicella profunda gen. nov., sp. nov., a novel piezophile isolated from deep seawater of the Mariana Trench

A novel piezophilic alphaproteobacterium, strain D4M1 T , was isolated from deep seawater of the Mariana Trench. 16S rRNA gene analysis showed that strain D4M1 T was most closely related to Oceanicella actignis PRQ‐67 T (94.2%), Oceanibium sediminis O448 T (94.2%), and Thioclava electrotropha ElOx9 T (94.1%). Phylogenetic analyses based on both 16S rRNA gene and genome sequences showed that strain D4M1 T formed an independent monophyletic branch paralleled with the genus Oceanicella in the family Rhodobacteraceae . Cells were Gram‐stain‐negative, aerobic short rods, and grew optimally at 37°C, pH 6.5, and 3.0% ( w / v ) NaCl. Strain D4M1 T was piezophilic with the optimum pressure of 10 MPa. The principal fatty acids were C 18:1 ω 7 c /C 18:1 ω 6 c and C 16:0 , major respiratory quinone was ubiquinone‐10, and predominant polar lipids were phosphatidylglycerol, phosphatidylethanolamine, and an unidentified aminophospholipid. The complete genome contained 5,468,583‐bp with a G + C content of 70.2 mol% and contained 4,855 protein‐coding genes and 78 RNA genes. Genomic analysis revealed abundant clues on bacterial high‐pressure adaptation and piezophilic lifestyle. The combined evidence shows that strain D4M1 T represents a novel species of a novel genus in the family Rhodobacteraceae , for which the name Paraoceanicella profunda gen. nov., sp. nov. is proposed (type strain D4M1 T  = MCCC 1K03820 T  = KCTC 72285 T ).