Halalkalicoccus subterraneus sp. nov., an extremely halophilic archaeon isolated from a subterranean halite deposit.

An extremely halophilic archaeon, designated strain GSM28, was isolated from a subterranean halite deposit in a Yunnan salt mine, China. Cells of the strain were observed to be cocci, non-motile and Gram-variable, and to require at least 15% (w/v) NaCl for growth (optimum 20%). Growth was found to occur in the ranges of 20-45 °C (optimum 42 °C) and pH 6.0-8.5 (optimum 7.5). Cells did not lyse in distilled water. Phylogenetic analysis based on 16S rRNA gene sequences indicated that this strain belongs to the genus Halalkalicoccus and shows 99.1% similarities with its close phylogenetic relative Halalkalicoccus paucihalophilus DSM 24557. Genomic ANI analysis showed that the DNA-DNA relatedness between strain GSM28 and the closely related species Hac. paucihalophilus DSM 24557 and Halalkalicoccus jeotgali B3 was 83.7% and 83.1%, respectively. The major polar lipids were determined to be phosphatidylglycerol, phosphatidylglycerol phosphate methyl ester, phosphatidylglycerol sulfate, sulfated mannosyl-glucosyl-glycerol diether-1 and two unidentified glycolipids. The DNA G + C content was determined to be 61.8 mol %. On the basis of physiological, biochemical tests and phylogenetic differentiations, strain GSM28 is concluded to represent a novel species in the genus Halalkalicoccus, for which the name Halalkalicoccus subterraneus sp. nov. is proposed. The type strain is GSM28 (= CGMCC 1.16344 = NBRC 113432).