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 D4M1T , was isolated from deep seawater of the Mariana Trench. 16S rRNA gene analysis showed that strain D4M1T was most closely related to Oceanicella actignis PRQ-67T (94.2%), Oceanibium sediminis O448T (94.2%), and Thioclava electrotropha ElOx9T (94.1%). Phylogenetic analyses based on both 16S rRNA gene and genome sequences showed that strain D4M1T 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 D4M1T was piezophilic with the optimum pressure of 10 MPa. The principal fatty acids were C18:1 ω7c/C18:1 ω6c and C16:0 , 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 D4M1T 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 D4M1T  = MCCC 1K03820T  = KCTC 72285T ).

Alteromonas indica Lin et al. 2018 is a later heterotypic synonym of Salinimonas sediminis Cao et al. 2018.

Alteromonas indica IO390401T was compared with Salinimonas sediminis N102T to examine the taxonomic relationship between the two type strains. The 16S rRNA gene sequence of A. indica IO390401T shared high similarity (99.9 %) with that of S. sediminis N102T. The results of phylogenetic analyses based on 16S rRNA gene sequences indicated that the two strains formed a tight cluster within the genus Salinimonas. Whole genomic comparison between the two strains revealed an average nucleotide identity of 99.2 % and a digital DNA-DNA hybridization estimate of 92.6 %, strongly indicating that the two strains represented a single species. In addition, neither strain displayed any striking difference in metabolic, physiological or chemotaxonomic features. Therefore, we propose Alteromonas indica as a later heterotypic synonym of Salinimonas sediminis.

Polyphasic taxonomic analysis of Parasedimentitalea marina gen. nov., sp. nov., a psychrotolerant bacterium isolated from deep sea water of the New Britain Trench.

A novel Rhodobacteraceae bacterium, strain W43T, was isolated from a deep-sea water sample from the New Britain Trench. Strain W43T exhibited the highest 16S rRNA gene sequence similarity of 96.5% to Sedimentitalea nanhaiensis DSM 24252T, Phaeobacter gallaeciensis DSM 26640T, Phaeobacter inhibens DSM 16374T, and Phaeobacter porticola P97T. Phylogenetic analysis of the 16S rRNA gene and phylogenomic analysis of the genome showed that strain W43T formed an independent monophyletic branch within the family Rhodobacteraceae. Strain W43T was Gram-stain-negative, rod-shaped, and grew optimally at 16-20°C, pH 6.5-7.0 and 2% (w/v) NaCl. The principal fatty acids were C18:1ω7c/C18:1ω6c, major respiratory quinone was ubiquinone-10 and predominant polar lipids were phosphatidylethanolamine, phosphatidylglycerol and diphosphatidylglycerol. The 5 080 916 bp long genome, comprising a circular chromosome and four plasmids, exhibits a G + C content of 55.9 mol%. The combined phenotypic, chemotaxonomic and molecular data show that strain W43T represents a novel species of a novel genus, for which the name Parasedimentitalea marina gen. nov. sp. nov. is proposed (type strain W43T = MCCC 1K03532T = KCTC 62635T).