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

Abstract

Three Gram-negative, chemoheterotrophic, non-motile, rod-shaped bacterial strains that accumulate poly-β-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 HTCC2516T, HTCC2523 and HTCC2597T, respectively. The most dominant fatty acid was 18 : 1ω7c in strains HTCC2516T and HTCC2523, and cyclo 19 : 0 in strain HTCC2597T. The type strains HTCC2516T and HTCC2597T were clearly differentiated by the presence or absence of 12 : 0, 12 : 1ω11c, 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 HTCC2516T (=ATCC BAA-861T=DSM 15982T=KCTC 12143T) and of Oceanicola batsensis sp. nov. with the type strain HTCC2597T (=ATCC BAA-863T=DSM 15984T=KCTC 12145T).