Phycocomes zhengii gen. nov., sp. nov., a marine bacterium of the family Rhodobacteraceae isolated from the phycosphere of Chlorella vulgaris

A Gram-stain-negative, motile with flagellum, ovoid- or rod-shaped, aerobic bacterium, was isolated from the phycosphere of the microalga Chlorellavulgaris and designated as strain LMIT002 T . The bacterium formed white, circular and smooth colonies on marine agar 2216 after 48 h incubation at 25 °C. On the basis of 16S rRNA gene sequence analysis, strain LMIT002 T was found to be affiliated with the family Rhodobacteraceae of the order Rhodobacterales, and formed a distinct group. The 16S rRNA gene sequence similarities between strain LMIT002 T and type strains in the family including Poseidonocella pacifica DSM 29316 T , Roseobacter litoralis and Rhodovulum sulfidophilum were 95.1, 95.0 and 95.0 %, respectively. Strain LMIT002 T grew optimally at 25 °C, pH 6.0 and in the presence of 2.0 % (w/v) NaCl. The genomic DNA G+C content was 67.0 mol% (the thermal denaturation method) or 66.9 % (genome sequencing). The sole respiratory quinone was ubiquinone-8, while the major fatty acids were summed feature 8 (C18 : 1 ω7с/C18 : 1 ω6с). The draft genome of strain LMIT002 T was sequenced and annotated, with the results showing that it had a total size of 4 607 780 bp and comprised 4557 genes. Functional genes encoding the production of vitamin B12, indole-3-acetic acid and transform dimethylsulphoniopropionate were detected. Given its distinct genomic, morphological and physiological differences from previously described type strains, strain LMIT002 T is proposed as a representative of a novel genus of the family Rhodobacteraceae, with the name Phycocomes zhengii gen. nov., sp. nov. The type strain is LMIT002 T (=KCTC 62390 T =CICC 24357 T ).