Characterization of a novel halophilic archaeon, Halobiforma haloterrestris gen. nov., sp. nov., and transfer of Natronobacterium nitratireducens to Halobiforma nitratireducens comb. nov.

Strain 135(T), a novel red-pigmented, aerobic, extremely halophilic member of the Archaea showing rod, coccus and slightly pleomorphic morphology, was isolated from hypersaline soil close to Aswan (Egypt). This organism is neutrophilic, motile and requires at least 2.2 M NaCl, but no MgCl2, for growth and exhibits optimal growth at 42 degrees C. Polar lipid analysis revealed the presence of sulfated triglycosyl diether and triglycosyl diether as the sole glycolipids as well as the absence of the glycerol diether analogue of phosphatidyl glycerosulfate. C20:C20 and C20:C25 core lipids are present in almost equal proportions. The G+C content of the DNA is 66.9 mol%. 16S rDNA analysis revealed that strain 135(T) was a member of the phyletic group defined by the family Halobacteriaceae, but there was a low degree of similarity to other members of this family. Highest similarity values of 96.4 and 93.8-94.3% were obtained to the 16S rDNA of Natronobacterium nitratireducens and Natronobacterium gregoryi, Natronococcus occultus and Natronococcus amylolyticus. Strain 135(T) is able to accumulate polyhydroxybutyrate as intracellular reserve material. On the basis of the data presented, strain 135(T) should be placed in a new genus, Halobiforma gen. nov. as Halobiforma haloterrestris sp. nov. The type strain is strain 135(T) (= DSM 13078(T) = JCM 11627(T)). Moreover, the transfer of Natronobacterium nitratireducens to Halobiforma nitratireducens comb. nov. is proposed.