Halorhabdus rudnickae sp. nov., a halophilic archaeon isolated from a salt mine borehole in Poland

Abstract

Two halophilic archaea, designated strains WSM-64T and WSM-66, were isolated from a sample taken from a borehole in the currently unexploited Barycz mining area belonging to the “Wieliczka” Salt Mine Company, in Poland. Strains are red pigmented and form non-motile cocci that stain Gram-negative. Strains WSM-64T and WSM-66 showed optimum growth at 40°C, in 20% NaCl and at pH 6.5–7.5. The strains were facultative anaerobes. The major polar lipids of the two strains were phosphatidylglycerol (PG2), phosphatidylglycerol phosphate methyl ester (PGP-Me) and sulfated diglycosyl diether (S-DGD). Menaquinone MK-8 was the major respiratory quinone. The DNA G+C content of strain WSM-64T was 61.2mol% by HPLC method; 61.0mol% by genome sequencing. Analysis of the almost complete 16S rRNA gene sequence indicated that the strains WSM-64T and WSM-66 (99.7% identity) represented a member of the genus Halorhabdus in the family Halobacteriaceae. Both strains formed a distinct cluster and were most closely related to Halorhabdus tiamatea SARL4BT and Halorhabdus utahensis AX-2T (DSM 12940T) (95.4% and 95.6%, respectively). ANI values of WSM-64T with the closest relative type strains were <78.5%. Based on 16S rRNA gene sequence and whole genome analyses, physiological and biochemical characteristics we describe a new species represented by strain WSM-64T (=DSM 29498T =CECT 8673T) for which we propose the name Halorhabdus rudnickae sp. nov.