Aequoribacter fuscus gen. nov., sp. nov., a new member of the family Halieaceae, isolated from coastal seawater.

A Gram-stain-negative, rod-shaped, obligately aerobic, nonflagellated, and chemoheterotrophic bacterium, designated IMCC3088, was isolated from coastal seawater of the Yellow Sea. The 16S rRNA gene sequence analysis indicated that this strain belonged to the family Halieaceae which shared the highest sequence similarities with Luminiphilus syltensis NOR5-1B (94.5%) and Halioglobus pacificus S1-72 (94.5%), followed by 92.3-94.3% sequence similarities with other species within the aforementioned family. Phylogenetic analyses demonstrated that strain IMCC3088 was robustly clustered with Luminiphilus syltensis NOR5-1B within the family Halieaceae. However, average amino acid identity (AAI), percentages of conserved proteins (POCP), average nucleotide identity (ANI), and alignment fraction (AF) between strain IMCC3088 and Luminiphilus syltensis NOR5-1B were 54.5%, 47.7%, 68.0%, and 16.5%, respectively, suggesting that they belonged to different genera. Whole-genome sequencing of strain IMCC3088 revealed a 3.1 Mbp genome size with a DNA G + C content of 51.7 mol%. The genome encoded diverse metabolic pathways including sulfur oxidation, phenol degradation, and proteorhodopsin phototrophy. Mono-unsaturated fatty acids were found to be the predominant cellular fatty acid components in the strain. Phosphatidylethanolamine, phosphatidylglycerol, and diphosphatidylglycerol were the primarily identified polar lipids, and ubiquinone-8 was identified as a major respiratory quinone. The taxonomic data collected herein suggested that strain IMCC3088 represented a novel genus and species of the family Halieaceae, for which the name Aequoribacter fuscus gen. nov., sp. nov. is proposed with the type strain (= KACC 15529 = NBRC 108213).