Oceanicola granulosus gen. nov., sp nov and Oceanicola batsensis sp nov., poly-β-hydroxybutyrate-producing marine bacteria in the order 'Rhodobacterales'

Three Gram-negative, chemoheterotrophic, non-motile, rod-shaped bacterial strains that accumulate poly-beta-hydroxybutyrate granules were isolated from the Bermuda Atlantic Time-series Study site by high-throughput culturing methods and characterized by polyphasic approaches. DNA-DNA hybridization, DNA G + C content and phylogenetic analyses based on 16S rRNA gene sequences divided the three isolates into two distinct genospecies that were clearly differentiated by fatty acid profiles, carbon source utilization patterns, antibiotic susceptibility and biochemical characteristics. The strains utilized a wide range of substrates, including pentoses, hexoses, oligosaccharides, sugar alcohols, organic acids and amino acids. DNA G + C contents were 71-5, 70-9 and 67-3 mol% for strains HTCC2516(T), HTCC2523 and HTCC2597(T), respectively. The most dominant fatty acid was 18: 1omega7c in strains HTCC2516(T) and HTCC2523, and cyclo 19: 0 in strain HTCC2597(T). The type strains HTCC2516(T) and HTCC2597(T) were clearly differentiated by the presence or absence of 12: 0, 12 : 10)11 c, 14: 0, 15 : 0 and methyl 18:1. Phylogenetic analyses indicated that the strains formed a distinct monophyletic lineage within the Roseobacter clade in the order 'Rhodobacterales' of the Alphaproteobacteria, and which did not associate with any of the described genera. Genotypic and phenotypic differences of the isolates from the previously described genera support the description of Oceanicola granulosus gen. nov., sp. nov. with the type strain HTCC2516(T) (=ATCC BAA-861(T) =DSM 15982(T) =KCTC 12143(T)) and of Oceanicola batsensis sp. nov. with the type strain HTCC2597(T) (= ATCC BAA-863(T) = DSM 15984(T) =KCTC 12145(T)).