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

Abstract

A Gram-staining-negative bacterium, strain DSG-S4-2T, 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-S4-2T 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-S4-2T 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-S4-2T 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 (C18 : 1ω7c and/or C18 : 1ω6c). 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-S4-2T was associated with the members of the genus Roseibium , with highest 16S rRNA gene sequence similarity to Roseibium denhamense OCh 254T (96.3 %) and Roseibium hamelinense OCh 368T (96.3 %). Based on the data presented above, it is concluded that strain DSG-S4-2T represents a novel species of the genus Roseibium , for which the name Roseibium aquae sp. nov. is proposed. The type strain is DSG-S4-2T ( = CGMCC 1.12426T = JCM 19310T).