Nibricoccus aquaticus gen. nov., sp. nov., a new genus of the family Opitutaceae isolated from hyporheic freshwater

A yellow-coloured, Gram-strain-negative, non-motile, cocci-shaped, strictly aerobic bacterium, designated HZ-65 ^T , was isolated from hyporheic freshwater in the Republic of Korea. Strain HZ-65 ^T grew at 15-37 °C (optimum, 25-30 °C), pH 5.5-9.0 (optimum, pH 7.0) and 0-0.5% NaCl (w/v; optimum at 0% NaCl). Phylogenetic analysis based on the 16S rRNA gene showed that strain HZ-65 ^T is a member of family Opitutaceae and is closely related to Opitutus terrae PB90-1 ^T (94.0% similarity), Cephaloticoccus primus CAG34 ^T (93.0 %), and Cephaloticoccus capnophilus CV41 ^T (92.7 %), while the similarities to other Opitutaceae-type strains were lower than 90.0 %. The DNA G+C content was 62.2 mol% and the quinone present was menaquinone-7. The predominant fatty acids were iso-C _{14: 0} , anteiso-C _{15: 0} , C _{16: 0} , and iso-C _{16: 0} , representing 70% of the total fatty acids. The major polar lipid profile consisted of phosphatidylethanolamine, phosphatidylglycerol and diphosphatidylglycerol. Analysis of the HZ-65 ^T genome revealed the presence of 300 genes that are involved in carbohydrate-active enzymes, which indicates the metabolic potential to degrade polysaccharides. The phenotypic, chemotaxonomic, genetic, and phylogenetic properties suggest that strain HZ-65 ^T represents a novel species in a new genus within the family Opitutaceae, for which the name Nibricoccus aquaticus gen. nov., sp. nov., is proposed. The type strain of Nibricoccus aquaticus is HZ-65 ^T (KACC 19333 ^T =NBRC 112907 ^T ).