Halomonas daqingensis sp. nov., a moderately halophilic bacterium isolated from an oilfield soil.

A Gram-negative, moderately halophilic, short rod-shaped, aerobic bacterium with peritrichous flagellae, strain DQD2-30(T), was isolated from a soil sample contaminated with crude oil from the Daqing oilfield in Heilongjiang Province, north-eastern China. The novel strain was capable of growth at NaCl concentrations of 1-15 % (w/v) [optimum at 5-10 % (w/v)]. Phylogenetic analyses based on 16S rRNA gene sequences showed that the novel strain belonged to the genus Halomonas in the class Gammaproteobacteria; the highest 16S rRNA gene sequence similarities were with Halomonas desiderata DSM 9502(T) (98.8 %), Halomonas campisalis A4(T) (96.6 %) and Halomonas gudaonensis CGMCC 1.6133(T) (95.1 %). The major cellular fatty acids of strain DQD2-30(T) were C(18 : 1)omega7c (43.97 %), C(19 : 0 )cyclo omega8c (23.37 %) and C(16 : 0) (14.83 %). The predominant respiratory lipoquinone was ubiquinone with nine isoprene units (Q9). The DNA G+C content was 67.0 mol%. The DNA-DNA hybridization values of strain DQD2-30(T) with the most closely related species of the genus Halomonas were 51.8 %, 28.4 % and 23.5 % for H. desiderata, H. campisalis and H. gudaonensis, respectively. Based on these analyses, strain DQD2-30(T )(=CGMCC 1.6443(T)=LMG 23896(T)) is proposed to represent the type strain of a novel species, Halomonas daqingensis sp. nov.