Draconibacterium mangrovi sp. Nov., isolated from mangrove sediment

Abstract

A marine bacterial strain, designated GM2-18T, was isolated from mangrove sediment sampled at Luoyang River estuary, Quan-zhou, 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 GM2-18T had maximum similarity values to ‘Draconibacterium filum’ F2T, 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 GM2-18T 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 GM2-18T 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-C15: 0, anteiso-C15: 0 and C17: 1 ω6c. The polar lipids were phosphatidylethanola-mine, a phospholipid and several unidentified lipids. The genomic size of strain GM2-18T was 5.9 Mb and the G+C content was 40.8 mol%. Gene prediction and annotation of strain GM2-18T 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 characteris-tics, strain GM2-18T represents a novel species within the genus Draconibacterium. Thus, Draconibacterium mangrovi sp. nov. is proposed with type strain GM2-18T (=MCCC 1K04382T=KCTC 72879T), isolated from mangrove sediment.