Dong Han, Heng-Lin Cui

School of Food and Biological Engineering, Jiangsu University, 301 Xuefu Road, Jingkou District, Zhenjiang, 212013, People’s Republic of China


Abstract

Two halophilic archaeal strains, R60^T and R61, were isolated from the brine of salted brown alga Laminaria. Cells of the two strains were observed to be rod-shaped, stain Gram-negative and to lyse in distilled water. Strain R60^T was found to contain gas vacuoles and to produce pink-pigmented colonies, while strain R61 lacked gas vacuoles and produces red-pigmented colonies. Both strains were found to be able to grow at 20–50 °C (optimum 30 °C), at 1.7–4.8 M NaCl (optimum 2.6–3.1 M NaCl), at 0–1.0 M MgCl₂ (optimum 0.005–0.1 M MgCl₂) and at pH 6.0–9.5 (optimum pH 7.0). The major polar lipids were identified as phosphatidylglycerol, phosphatidylglycerol phosphate methyl ester, phosphatidylglycerol sulfate and one major glycolipid chromatographically identical to a sulfated mannosyl glucosyl diether produced by Halorubrum members of the Halobacteriaceae. The 16S rRNA gene sequences of the two strains were 99.9 % identical, showing 94.6–98.0 % similarity to those of members of the genus Halorubrum. The EF-2 gene similarity between strains R60T and R60 was 100 % and showed 84.6–94.5 % similarity to those of members of the genus Halorubrum. The DNA G+C contents of the two strains were determined to be 63.0 mol %. The DNA–DNA hybridization value between strain R60T and strain R61 was 92 % and the two strains showed low DNA–DNA relatedness with the most related members of Halorubrum. The phenotypic, chemotaxonomic and phylogenetic properties suggest that strain R60^T (= CGMCC 1.12689^T = JCM 30040^T) and strain R61 (= CGMCC 1.12696) represent a novel species of the genus Halorubrum, for which the name Halorubrum laminariae sp. nov. is proposed

Keywords:Halorubrum laminariae sp. nov., Halophilic archaeon, Salted brown alga .