Vibrio mangrovi sp. nov., a diazotrophic bacterium isolated from mangrove-associated wild rice (Poteresia coarctata   Tateoka)

The taxonomic status of a nitrogen-fixing bacterium, strain MSSRF38^T, isolated from the rhizosphere of mangrove-associated wild rice (Porteresia coarctata Tateoka), in Pichavaram, India, was studied using a polyphasic approach. Phylogenetic analyses based on 16S rRNA gene sequences indicated that the novel strain MSSRF38^T was most closely related to Vibrio ruber DSM 16370^T (98.3% gene sequence similarity), Vibrio rhizosphaerae DSM 18581^T (98.2% sequence similarity) and <96% to the remaining Vibrio species. Multilocus sequence analysis using ftsZ, gapA, gyrB and mreB genes showed low levels of gene sequence similarities (82–90%) with all species of the genus Vibrio with validly published names, indicating that strain MSSRF38^T occupies a distinct phylogenetic position. DNA–DNA hybridization experiments showed that strain MSSRF38^T had <70% DNA–DNA similarity to its closest neighbours V. ruber DSM 16370^T (27.4%) and V. rhizosphaerae DSM 18581^T (12.1%). Strain MSSRF38^T could be differentiated from its relatives on the basis of several phenotypic characteristics. The major fatty acids were feature 3 (including C_16:1ω7c and/or C_15:0 iso 2-OH), C16:0, C_18:1ω7c, C_14:0 and C_12:0. The DNA G+C content was 45.4 mol%. Based on genotypic, phenotypic, chemotaxonomic and DNA–DNA analyses, the name Vibrio mangrovi sp. nov. (type strain MSSRF38^T=LMG 24290^T=DSM 19641^T) is proposed for this novel taxon.