Draconibacterium mangrovi sp. nov., isolated from mangrove sediment

A marine bacterial strain, designated GM2-18(T), was isolated from mangrove sediment sampled at Luoyang River estuary, Quanzhou, PR China. Cells were Gram-stain-negative, slightly curved long rod-shaped and facultatively anaerobic with no flagellum. Catalase activity was found to be weak-positive and oxidase-positive. It had no ability to degrade or hydrolyse substrates including skimmed milk, cellulose, starch and Tweens (40, 60 and 80). The 16S rRNA gene sequence of strain GM2-18(T) had maximum similarity values to 'Draconibacterium filum' F2(T), Draconibacterium sediminis JN14CK-3(T) and Draconibacterium orientale FH5T of 98.0, 97.8 and 97.4%, respectively. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain GM2-18(T) was affiliated to the genus Draconibacterium and formed a Glade with an uncultured bacterium clone identified from mangrove environment. Average nucleotide identity values and DNA-DNA hybridization estimates of strain GM2-18(T) compared to its Draconibacterium relatives strongly supported that it belonged to a new species. The respiratory quinone was menaquinone MK-7. The major fatty acids (>10%) consisted of iso-C-15:0, anteiso-C-15(:0) and C-17:1 omega 6c. The polar lipids were phosphatidylethanolamine, a phospholipid and several unidentified lipids. The genomic size of strain GM2-18 1 was 5.9 Mb and the G+C content was 40.8mol%. Gene prediction and annotation of strain GM2-18(T) indicated that there was a nitrogen-fixing gene cluster encoding nitrogenase molybdenum-iron protein and related proteins responsible for nitrogen fixation. Based on the above characteristics, strain GM2-18(T) represents a novel species within the genus Draconibacterium. Thus, Draconibacterium mangrovi sp. nov. is proposed with type strain GM2-18(T) (=MCCC 1K04382(T)=KCIC 72879(T)), isolated from mangrove sediment.