Halomonas zhaodongensis sp. nov., a slightly halophilic bacterium isolated from saline-alkaline soils in Zhaodong, China

Abstract

A slightly halophilic bacterium (strain NEAU-ST10-25(T)) was isolated from saline-alkaline soils in Zhaodong City, Heilongjiang Province, China. The strain is a Gram-negative, aerobic motile rod. It accumulates poly-β-hydroxyalkanoate and produces exopolysaccharide. It produces beige-yellow colonies. Growth occurs at NaCl concentrations (w/v) of 0-15 % (optimum 3 %), at temperatures of 4-60 °C (optimum 35 °C) and at pH 6-12 (optimum pH 9). Its G+C content is 53.8 mol%. Phylogenetic analyses based on the separate 16S rRNA gene and concatenation of the 16S rRNA, gyrB and rpoD genes indicate that it belongs to the genus Halomonas in the class Gammaproteobacteria. The most phylogenetically related species is Halomonas alkaliphila DSM 16354(T), with which strain NEAU-ST10-25(T) showed 16S rRNA, gyrB and rpoD gene sequence similarities of 99.2, 82.3 and 88.2 %, respectively. The results of DNA-DNA hybridization assays showed 60.47 ± 0.69 % DNA relatedness between strain NEAU-ST10-25(T) and H. alkaliphila DSM 16354(T), 42.43 ± 0.37 % between strain NEAU-ST10-25(T) and Halomonas venusta DSM 4743(T) and 30.62 ± 0.43 % between strain NEAU-ST10-25(T) and Halomonas hydrothermalis DSM 15725(T). The major fatty acids are C18:1 ω7c (62.3 %), C16:0 (17.6 %), C16:1 ω7c/C16:1 ω6c (7.7 %), C14:0 (2.9 %), C12:0 3-OH (2.8 %), C10:0 (2.1 %) and C18:1 ω9c (1.6 %) and the predominant respiratory quinone is ubiquinone 9 (Q-9). The proposed name is Halomonas zhaodongensis, NEAU-ST10-25(T) (=CGMCC 1.12286(T) = DSM 25869(T)) being the type strain.