gen. nov., sp. nov., isolated from marine sediment, and description of fam. nov. and fam. nov.

A Gram-stain-negative, facultatively anaerobic, oxidase-negative and catalase-positive predatory bacillus, designated strain V1718, was isolated from Xiaoshi Island, PR China. Strain V1718 was found to be closely related to SEH01, with 89.8 % similarity in the 16S rRNA gene sequence, followed by FA350 with a similarity of 88.4 %. Strain V1718 had the ability to prey on other bacteria, and selective predation on members of , and occurred with the strain. Growth was observed within the range of 20-45 °C (optimal at 37 °C), pH 6.5-9.0 (optimal at pH 8.0) and 1-10 % NaCl (optimal at 3-4 %, w/v). The predominant cellular fatty acids in strain V1718 were iso-C (53.0 %) and C (19.1 %). The major polar lipids present in the strain were phosphatidylglycerol and phosphatidylethanolamine, and the respiratory quinone was menaquinone MK-7. The complete genome sequence of strain V1718 was 5 847 748 bp with a G+C content of 55.2 mol%. The topology of the phylogenomic tree indicated that strain V1718 forms a separate branch in the same clade with the genus and the family . The average nucleotide identity and average amino acid identity values were 66.4 and 48.6 %, respectively, with FA350 (type species of ) and 66.8 % and 48.9 % with B210 (type species of ). The genes related to biosynthesis pathways of several important chemical compounds could not be found in the genome of strain V1718, which was predicted to be the intrinsic reason for predation in this group. The physiological, biochemical and phylogenetic properties of strain V1718 suggest that it belongs to a novel family distinct from other culturable bradymonabacteria. The name gen. nov., sp. nov. is proposed, with strain V1718 (=KCTC 72082=MCCC 1H00380) as type strain; the name fam. nov. is also proposed. Meanwhile, the genus can also be taxonomic classified as fam. nov. Thus, two novel families and a novel genus of the order are proposed in this paper.