Identification and genomic analysis of Pseudosulfitobacter koreense sp. nov. isolated from toxin-producing dinoflagellate Alexandrium pacificum

The bacterial strain AP-MA-4(T) isolated from the marine dinoflagellate Alexandrium pacificum (KCTC AG60911), was subjected to a taxonomic analysis. Cells of strain AP-MA-4(T) were Gram-stain-negative, aerobic, rod-shaped, optimum growth at 20 degrees C, pH 7.0, in the presence of 5% (w/v) NaCl. Strain AP-MA-4(T) shared the highest 16S rRNA gene sequence similarity to Pseudosulfitobacter pseudonitzschiae DSM 26824(T) (98.5%), followed by Ascidiaceihabitans donghaensis RSS1-M3(T) (96.3%), Pseudoseohaeicola caenipelagi BS-W13(T) (95.7%), and Sulfitobacter pontiacus CHLG 10(T) (95.3%). Based on 16S rRNA phylogeny, strain AP-MA-4(T) is phylogenetically closely related to Pseudosulfitobacter pseudonitzschiae (type species of Pseudosulfitobacter) and could be distinguished from the type species based on their phenotypic properties. The genome length of strain AP-MA-4(T) was 3.48 Mbp with a 62.9% G + C content. The average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) values between strain AP-MA-4( T) and its closely related type strains were 72.2-83.3 and 18.2-27.6%, respectively. Summed feature 8 (C-18:1 omega 7c and/or C-18:1 omega 6c) was identified the major fatty acids (> 10%). Phosphatidylglycerol (PG), phosphatidylethanolamine (PE), and phospholipid (PL) were demonstrated as the major polar lipids. The major respiratory quinone is ubiquinone-10 (Q-10). Based on genotypic and phenotypic features, strain AP-MA-4(T) (= KCTC 92289(T) = GDMCC 1.3585(T)) represents a new Pseudosulfitobacter species, in which the name Pseudosulfitobacter koreense sp. nov. is proposed.