Halapricum salinum gen. nov., sp nov., an extremely halophilic archaeon isolated from non-purified solar salt

Abstract

A halophilic archaeal strain, designated CBA1105(T), was isolated from non-purified solar salt. Strain CBA1105(T) was found to have three 16S rRNA genes, rrnA, rrnB and rrnC; similarities between the 16S rRNA gene sequences were 99.5-99.7 %. The phylogenetic analysis of the 16S rRNA gene sequences showed that strain CBA1105(T) forms a distinct clade with the strains of the closely related genera, Halorientalis and Halorhabdus, with similarities of 94.2 % and 93.9-94.2 %, respectively. Multilocus sequence analysis confirmed that strain CBA1105(T) is closely related to the genus Halorhabdus or Halorientalis. Growth of the strain was observed in 15-30 % NaCl (w/v; optimum 20 %), at 30-45 A degrees C (optimum 37 A degrees C) and pH 7.0-8.0 (optimum pH 7.0) and with 0-0.5 M MgCl2 center dot 6H(2)O (optimum 0.05-0.2 M). The cells of the strain were observed to be Gram-stain negative and pleomorphic with coccoid or ovoid-shape. The cells lysed in distilled water. Tweens 20, 40 and 80 were found to be hydrolysed but starch, casein and gelatine were not. The cells were unable to reduce nitrate under aerobic conditions. Assays for indole formation and urease activity were negative and no growth was observed under anaerobic conditions. Cells were found to be able to utilize l-glutamate, d-glucose, l-maltose, d-mannose and sucrose as sole carbon sources. The polar lipids were identified as phosphatidylglycerol, phosphatidylglycerol phosphate methyl ester, unidentified glycolipids and an unidentified phospholipid. The G+C content of strain CBA1105(T) was determined to be 66.0 mol%. The phenotypic, chemotaxonomic and phylogenetic properties suggest that the strain represents a novel species of a novel genus within the family Halobacteriaceae, for which the name Halapricum salinum is proposed with CBA1105(T) (= KCTC 4202(T) = JCM 19729(T)) as the type strain.