Halomonas lutescens sp. nov., a halophilic bacterium isolated from a lake sediment

A novel, Gram-stain-negative, facultatively anaerobic, halophilic bacterium, designated strain Q1UT, was isolated from a sediment sample collected from Qinghai Lake, PR China. The cells of the strain were short rod-shaped (0.2-0.3×0.6-2.5 µm) and non-motile. Strain Q1UT formed yellowish colonies and grew at temperatures of 2-37 °C (optimum 30-33 °C), at pH 6.0-9.0 (optimum pH 7.0) and in the presence of 0-20 % (w/v) NaCl (optimum 7.5 %). The major cellular fatty acids were C18 : 1ω7c (58.6 %), C16 : 1ω7c and/or C16 : 1ω6c (14.8 %) and C16 : 0 (10.1 %). The polar lipids were identified as diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, unknown phospholipid and unknown lipids. The genomic DNA G+C content was 61.5 mol%, and the predominant respiratory ubiquinone Q-9. Based on phylogenetic analysis of the 16S rRNA gene sequences and concatenated 16S rRNA, gyrB and rpoD gene sequences, the isolate was found to belong to the genus Halomonas in the class Gammaproteobacteria. The most closely related species were Halomonas venusta DSM 4743T (98.3 % 16S rRNA sequence similarity), Halomonas songnenensis DSM 25870T (98.2 %) and Halomonas hydrothermalis DSM 15725T (98.2 %). DNA-DNA relatedness values between strain Q1UT and the type strains of eight other species of the genus Halomonas ranged from 21.3 % to 10.1 %. On the basis of phenotypic, phylogenetic and chemotaxonomic analyses, and DNA-DNA hybridization relatedness values, strain Q1UT is considered to represent a novel species of the genus Halomonas; the name Halomonas lutescens sp. nov. is proposed. The type strain is Q1UT (=CGMCC 1.15122T=KCTC 42517T).