Marinobacter aquaticus sp nov., a moderately halophilic bacterium from a solar saltern

A moderately halophilic bacterium designated strain M6-53(T) was isolated from water of a pond from a marine saltern located in Huelva, south-west Spain. Cells of the strain were Gram-stain-negative, strictly aerobic, motile, slightly curved rods, able to grow in media containing 5-25% (w/v) NaCl (optimal growth at 10 %, w/v), at temperatures from 20 to 40 degrees C (optimally at 37 degrees C) and at pH 6.5-9 (optimally at pH 7.0). Phylogenetic analysis based on 16S rRNA gene sequences placed the new isolate within the genus Marinobacter, with the type strains of the most closely related species being Marinobacter persicus IBRC-M 10445(T) (98.5% similarity), Marinobacter oulmenensis Set74(T) (97.2 %) and Marinobacter hydrocarbonoclasticus ATCC 49840(T) (97.1 %). The major fatty acids present in strain M6-53(T) were C-18:1 omega 9c (29.5 %), C-16:0 (26.7 %), C-12:0 3-OH (15.1 %), C-18:0 (10.2 %) and C-16:0 omega 9c (9.6 %). The G+C content of the genomic DNA for this strain was determined to be 56.4 mol%. The DNA-DNA hybridization values between strain M6-53(T) and M. persicus CECT 7991(T), M. oulmenensis CECT 7499(T) and M. hydrocarbonoclasticus DSM 50418 were 8, 41 and 38 %, respectively. These values are lower than the accepted 70% threshold and showed that the new isolate represented a different species within the genus Marinobacter. Phylogenetic analysis based on the 16S rRNA gene sequence and the phenotypic, genotypic and chemotaxonomic features of this new isolate support the placement of strain M6-53(T) as a representative of a novel species of the genus Marinobacter, for which we propose the name Marinobacter aquaticus sp. nov., with strain M6-53(T) (= CECT 9228(T) = LMG 30006(T)) as the type strain.