Natronoarchaeum mannanilyticum gen. nov., sp. nov., an aerobic, extremely halophilic archaeon isolated from commercial salt

Strain YSM-123(T) was isolated from commercial salt made from Japanese seawater in Niigata prefecture. Optimal NaCl and Mg2+ concentrations for growth were 4.0-4.5 M and 5 mM, respectively. The isolate was a mesophilic and slightly alkaliphilic haloarchaeon, whose optimal growth temperature and pH were 37 degrees C and pH 8.0-9.0. Phylogenetic analysis based on 16S rRNA gene sequence analysis suggested that strain YSM-123(T) is a member of the phylogenetic group defined by the family Halobacteriaceae, but there were low similarities to type strains of other genera of this family (<= 90%); for example, Halococcus (similarity <89%), Halostagnicola (<89%), Natronolimnobius (<89%), Halobiforma (<90%), Haloterrigena (<90%), Halovivax (<90%), Natrialba (<90%), Natronobacterium (<90%) and Natronococcus (<90%). The G+C content of the DNA was 63 mol%. Polar lipid analysis revealed the presence of phosphatidylglycerol, phosphatidylglycerophosphate methyl ester, disulfated diglycosyl diether and an unknown glycolipid. On the basis of the data presented, we propose that strain YSM-123(T) should be placed in a new genus and species, Natronoarchaeum mannanilyticum gen. nov., sp. nov. The type strain of Natronoarchaeum mannanilyticum is strain YSM-123(T) (=JCM 16328(T) =CECT 7565(T)).