Roseibium aquae sp. nov., isolated from a saline lake.

ABSTRACT

A Gram-staining-negative bacterium, strain DSG-S4-2(T), was isolated from Dasugan Lake, a saline lake (salinity 3.1%, w/v) in Qaidam basin, Qinghai, China and its taxonomic position was determined by using a polyphasic approach. Cells of strain DSG-S4-2(T) were non-spore-forming rods, 0.5-0.8 µm wide and 1.2-3.8 µm long and motile by means of a single polar flagellum. Strain DSG-S4-2(T) was strictly heterotrophic and aerobic, catalase-positive and oxidase-negative. PufLM and coxL genes were present, bacteriochlorophyll a (BChl a) and a carotenoid pigment were produced. Growth was observed in the presence of 0-8.0% (w/v) NaCl (optimum, 1.0-2.0%), at 20-40 °C (optimum, 35 °C) and pH 6.5-10.5 (optimum, pH 7.5-8.0). Strain DSG-S4-2(T) contained Q-10 as the sole respiratory quinone. The polar lipids contained two aminolipids, diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, phosphatidylmonomethylethanolamine, sulphoquinovosyldiacylglyceride, phosphatidylcholine and some unknown phospholipids, like the other members of the genus Roseibium. The predominant fatty acid (>70%) was summed feature 8 (C(18  1)ω7c and/or C(18  1)ω6c). The DNA G+C content was 61.4 mol% (determined from melting temperature). Phylogenetic trees (neighbour-joining, maximum-likelihood and maximum-parsimony) based on 16S rRNA gene sequences showed that strain DSG-S4-2(T) was associated with the members of the genus Roseibium, with highest 16S rRNA gene sequence similarity to Roseibium denhamense OCh 254(T) (96.3%) and Roseibium hamelinense OCh 368(T) (96.3%). Based on the data presented above, it is concluded that strain DSG-S4-2(T) represents a novel species of the genus Roseibium, for which the name Roseibium aquae sp. nov. is proposed. The type strain is DSG-S4-2(T) ( = CGMCC 1.12426(T) = JCM 19310(T)).