Natronoarchaeum philippinense sp. nov., a haloarchaeon isolated from commercial solar salt

A Gram-staining-negative, pleomorphic, aerobic, halophilic archaeon, designated strain 294-194-5(T), was isolated in Japan from commercial solar salt imported from the Philippines. Colonies of strain 294-194-5(T) were translucent and red. Strain 294-194-5(T) was able to grow at 20-50 °C (optimum, 37-45 °C), with 14-30 % (w/v) NaCl (optimum, 18 %), and at pH 6.5-8.5 (optimum, pH 8.0). MgCl2 was not required for growth. Phylogenetic analysis based on 16S rRNA gene sequence similarities showed that strain 294-194-5(T) was most closely related to Natronoarchaeum mannanilyticum YSM-123(T) (96.8-97.1 % sequence similarities). The major polar lipids of the novel strain were the C20C20 and C20C25 derivatives of phosphatidylglycerol and phosphatidylglycerol phosphate methyl ester and the same glycolipids (disulfated diglycosyl diether and one unidentified glycolipid) as detected in N. mannanilyticum YSM-123(T). The DNA G+C content of strain 294-194-5(T) was 63.0 mol%. The DNA-DNA relatedness values between the novel strain and N. mannanilyticum YSM-123(T)were 46.5 % and 48.5 % (reciprocal). Based on these data, strain 294-194-5(T) represents a novel species of the genus Natronoarchaeum, for which the name Natronoarchaeum philippinense sp. nov. is proposed. The type strain is 294-194-5(T) ( = JCM 16593(T) = CECT 7630(T)).