Halarchaeum grantii sp. nov., a moderately acidophilic haloarchaeon isolated from a commercial salt sample

Three moderately acidophilic, halophilic archaeal strains, MH1-243-3 T , MH1-243-5 and MH1-243-6, were isolated from a commercial salt sample made from seawater in Okinawa, Japan. Cells of the three strains were pleomorphic and stained Gram-negative. Colonies of the strains were orange–red-pigmented. Strain MH1-243-3 T was able to grow at 15–27 % (w/v) NaCl (optimum 24 °C), at pH 4.5–6.5 (pH 5.5) and at 35–50 °C (45 °C). Strains MH1-243-5 and MH1-243-6 grew within slightly different ranges (shown in text). The 16S rRNA gene sequences of the three strains were identical, and the closest phylogenetic relative was Halarchaeum salinum MH1-34-1 T with 97.0 % similarity. The rpoB ′ gene sequences of the three strains were also identical, and the closest phylogenetic relative was Halarchaeum acidiphilum JCM 16109 T with 92.0 % similarity. The DNA G+C content of MH1-243-3 T , MH1-243-5 and MH1-243-6 was 65.2 mol%. The levels of DNA–DNA relatedness amongst the three strains were 84.1–99.8 %, while that between MH1-243-3 T and H. salinum MH1-34-1 T was 30.6 % and 31.6 % (reciprocally), and those between MH1-243-3 T and type strains of other species in the genus Halarchaeum were 42.3–29.4 %. Based on the phenotypic, genotypic and phylogenetic analyses, it is proposed that the isolates should represent a novel species of the genus Halarchaeum , for which the name Halarchaeum grantii sp. nov. is proposed. The type strain is MH1-243-3 T ( = JCM 19585 T  = KCTC 4142 T ), isolated from commercial sea salt produced in Okinawa, Japan. MH1-243-5 ( = JCM 19586) and MH1-243-6 ( = JCM 18422) are additional strains of the species.