A Gram-staining negative, aerobic, oval-shaped bacterium, designated strain PTG4-2T, was isolated from deep-sea sediment of the Indian Ocean. Growth was observed with 1-9 % (w/v) NaCl with optimal growth with 3 %, at pH 6.0-10.0 with an optimum of pH 7.0, and at 4-40 °C with an optimum of 30 °C. Positive for catalase and oxidase. The results of a 16S rRNA gene sequence comparison indicated that PTG4-2T was most closely related to Acuticoccus yangtzensis JL1095T (97.3 %), followed by Acuticoccus kandeliae J103T (96.5 %), all other species shared <93 % sequence similarity. The results of phylogenetic analysis based on 16S rRNA gene sequences indicated that PTG4-2T forms a distinct lineage within the genus Acuticoccus, and revealed that the genus Acuticoccus forms a novel family-level clade in the order Rhizobiales. The ANI and the DNA-DNA hybridization estimate values between PTG4-2T and two type strains (A. yangtzensis JL1095T and A. kandeliae J103T) were 79.9-76.2 % and 23.1-20.8 %, respectively. PTG4-2T contained Q-10 as the predominant ubiquinone. The principal fatty acids (>5 %) were summed feature 8 [C18 : 1ω7c/ω6c (72.2 %)], C18 : 0 (8.4 %), C20 : 1ω7c (6.4 %) and C16 : 0 (6.3 %). The polar lipids consisted of phosphatidylglycerol, three unidentified phospholipids, two unidentified glycolipids, one unidentified aminolipid and one unknown lipid. The DNA G+C content of PTG4-2T is 69.2 mol%. On the basis of the polyphasic taxonomic evidence presented in this study, PTG4-2T should be classified as representing a novel species of the genus Acuticoccus, for which the name Acuticoccus sediminis sp. nov. is proposed, with the type strain PTG4-2T (=MCCC 1A01274T=KCTC 52323T). In addition, a novel family, Acuticoccaceae fam. nov., is proposed to accommodate the genus Acuticoccus.
Keywords: Acuticoccaceae fam. nov.; Acuticoccus sediminis sp. nov.; Indian Ocean; deep-sea sediment.