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 FH5^T 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 clade 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  ω6c. The polar lipids were phosphatidylethanolamine, a phospholipid and several unidentified lipids. The genomic size of strain GM2-18^T was 5.9 Mb and the G+C content was 40.8 mol%. 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=KCTC 72879^T), isolated from mangrove sediment.