Description of Kushneria aurantia gen. nov., sp. nov., a novel member of the family Halomonadaceae, and a proposal for reclassification of Halomonas marisflavi as Kushneria marisflavi comb. nov., of Halomonas indalinina as Kushneria indalinina comb. nov. and of Halomonas avicenniae as Kushneria avicenniae comb. nov.

An aerobic, moderately halophilic, Gram-negative, motile, non-sporulating rod-shaped bacterium, designated strain A10(T), was isolated from the surface of leaves of the black mangrove Avicennia germinans and was subjected to a polyphasic taxonomic study. Strain A10(T) was able to grow at NaCl concentrations in the range 5-17.5 % (w/v) with optimum growth at 10 % (w/v) NaCl. Growth occurred at temperatures of 20-40 degrees C (optimal growth at 37 degrees C) and pH 5.5-8.5 (optimal growth at pH 7.0-8.0). The major respiratory quinone was ubiquinone 9. The major fatty acids were C(16 : 0), C(18 : 1)omega7c, C(19 : 0) cyclo omega8c and C(12 : 0) 3-OH. The polar lipids were phosphatidylglycerol, diphosphatidylglycerol, phosphatidylethanolamine, and unidentified phospholipids, glycolipids and an aminoglycolipid. Phylogenetic analysis based on 16S rRNA gene sequence comparisons revealed that strain A10(T) is closely related to Halomonas avicenniae MW2a(T) (95.7 % sequence similarity), Halomonas marisflavi SW32(T) (95.2 %) and Halomonas indalinina GC2.1(T) (95.0 %). Strain A10(T) formed a coherent phylogenetic branch with these three species, separated from other species of Halomonas and closely related genera (with 16S rRNA gene sequence similarities below 94.0 %). A complete 23S rRNA gene sequence comparison of strain A10(T) with closely related species confirmed the phylogenetic position of the novel isolate, forming a branch with the species Halomonas avicenniae, Halomonas indalinina and Halomonas marisflavi, separated from other species of the genera belonging to the family Halomonadaceae (showing sequence similarities below 91.7 %). DNA-DNA hybridization studies between strain A10(T) and Halomonas avicenniae MW2a(T), Halomonas marisflavi DSM 15357(T) and Halomonas indalinina CG2.1(T) were 21, 17 and 10 %, respectively. These levels of DNA-DNA relatedness were low enough to classify strain A10(T) as representing a genotypically distinct species. Overall, the phenotypic, genotypic, chemotaxonomic and phylogenetic results demonstrated that strain A10(T) represents a new genus and species. The name Kushneria aurantia gen. nov., sp. nov. is proposed, with strain A10(T) (=CCM 7415(T)=CECT 7220(T)) as the type strain. This is the type species of the new proposed genus, which belongs to the family Halomonadaceae. In addition, our data support the placement of the species Halomonas marisflavi, Halomonas indalinina and Halomonas avicenniae within this new genus, as Kushneria marisflavi comb. nov., Kushneria indalinina comb. nov. and Kushneria avicenniae comb. nov., respectively.