Thiosulfatihalobacter marinus gen. nov. sp. nov., a novel member of the family Roseobacteraceae, isolated from the West Pacific Ocean

Two strains (GL-11-2(T) and ZH2-Y79) were isolated from the seawater collected from the West Pacific Ocean and the East China Sea, respectively. Cells were Gram-stain-negative, strictly aerobic, non-motile and rod-shaped. Cells grew in the medium containing 0.5-7.5% NaCl (w/v, optimum, 1.0-3.0%), at pH 6.0-8.0 (optimum, pH 6.5-7.0) and at 4-40 degrees C (optimum, 30 degrees C). H2S production occurred in marine broth supplemented with sodium thiosulphate. The almost-complete 16S rRNA gene sequences of the two isolates were identical, and exhibited the highest similarity to Pseudoruegeria aquimaris JCM 13603(T) (97.5%), followed by Ruegeria conchae TW15(T) (97.2%), Shimia aestuarii DSM 15283(T) (97.1%) and Ruegeria lacuscaerulensis ITI-1157(T) (97.0%). Phylogenetic analysis revealed that the isolates were affiliated with the family Roseobacteraceae and represented an independent lineage. The sole isoprenoid quinone was ubiquinone 10. The principal fatty acids were summed feature 8 (C-18:1 omega 7c and/or C-18:1 omega 6c) and cyclo-C-19:0 omega 8c. The major polar lipids were phosphatidylglycerol, phosphatidylethanolamine, phosphatidylcholine and diphosphatidylglycerol. The DNA G+C content was 62.3mol%. The orthologous average nucleotide identity, in silico DNA-DNA hybridization and average amino acid identity values among the genomes of strain GL-11-2(T) and the reference strains were 73.2-79.0, 20.3-22.5 and 66.0-80.8%, respectively. Strains GL-11-2(T) and ZH2-Y79 possessed complete metabolic pathways for thiosulphate oxidation, dissimilatory nitrate reduction and denitrification. Phylogenetic distinctiveness, chemotaxonomic differences and phenotypic properties revealed that the isolates represent a novel genus and species of the family Roseobacteraceae, belonging to the class Alphaproteobacteria, for which the name Thiosulfatihalobacter marinus gen. nov., sp. nov. (type strain, GL-11-2(T)=KCTC 82723(T)=MCCC M20691(T)) is proposed.

Automated summary

Two new strains of bacteria were isolated from seawater samples collected from the West Pacific Ocean and the East China Sea. Through phylogenetic analysis and physiological studies, these strains were identified as a novel genus and species belonging to the family Roseobacteraceae, and named Thiosulfatihalobacter marinus.