RESUMO
Three halophilic archaeal strains, MH2-243-1(T), MH2-93-1 and MH2-91-1 were isolated from commercial salt samples from Japan, Australia, and Bolivia. Strain MH2-243-1(T) was able to grow in the presence of 12-30% (w/v) NaCl (optimum, 18% NaCl), at pH 4.5-7.0 (optimum, pH 6.0) and at 20-60 °C (optimum, 40 °C). Strains MH2-91-1 and MH2-93-1 grew in slightly different ranges. The orthologous 16S rRNA gene sequences of the three strains were almost identical (99.8-99.9% similarities), and the closest relative was Salarchaeum japonicum JCM 16327(T) with 94.2-94.3% 16S rRNA gene sequence similarities, followed by strains of members of the closely related genera Halobacterium and Halarchaeum . The RNA polymerase subunit B' gene (rpoB') sequence also showed the highest similarity (86.6%) to that of Salarchaeum japonicum JCM 16327(T). The DNA G+C contents of strains MH2-243-1(T), MH2-93-1 and MH2-91-1 were 68.5, 68.8 and 68.3 mol%, respectively. DNA-DNA relatedness values amongst the three strains were 97-99%. The polar lipids of the three strains were phosphatidylglycerol, phosphatidylglycerol phosphate methyl ester, and at least seven unidentified glycolipids. The polar lipid composition differed from those of Salarchaeum japonicum and species of the genera Halobacterium and Halarchaeum . Based on the phenotypic and phylogenetic analyses, it is proposed that the isolates represent a novel species of a new genus, for which the name Halocalculus aciditolerans gen. nov., sp. nov. is proposed. The type strain of the type species is MH2-243-1(T) (â=âJCM 19596(T)â=KCTC 4149(T)) isolated from solar salt produced in Japan. MH2-93-1 (â=âJCM 19595) and MH2-91-1 (â=âJCM 19594) are additional strains of the type species.
Assuntos
Halobacteriaceae/classificação , Filogenia , Cloreto de Sódio , Austrália , Bolívia , DNA Arqueal/genética , Genes Arqueais , Glicolipídeos/química , Halobacteriaceae/genética , Halobacteriaceae/isolamento & purificação , Japão , Lipídeos/química , Dados de Sequência Molecular , Hibridização de Ácido Nucleico , RNA Ribossômico 16S/genética , Análise de Sequência de DNARESUMO
Two extremely halophilic archaea, strains MGY-184(T) and MGY-205, were isolated from sea salt produced in Japan and rock salt imported from Bolivia, respectively. Both strains were pleomorphic, non-motile, Gram-negative and required more than 5â% (w/v) NaCl for growth, with optimum at 9-12â%, in the presence of 2â% (w/v) MgCl2â.â6H2O. In the presence of 18â% (w/v) MgCl2â.â6H2O, however, both strains showed growth even at 1.0â% (w/v) NaCl. Both strains possessed two 16S rRNA genes (rrnA and rrnB), and they revealed closest similarity to Halobaculum gomorrense JCM 9908(T), the single species with a validly published name of the genus Halobaculum, with similarity of 97.8â%. The rrnA and rrnB genes of both strains were 100â% similar. The rrnA genes were 97.6â% similar to the rrnB genes in both strains. DNA G+C contents of strains MGY-184(T) and MGY-205 were 67.0 and 67.4 mol%, respectively. Polar lipid analysis revealed that the two strains contained phosphatidylglycerol and phosphatidylglycerol phosphate methyl ester derived from C20C20 archaeol. The DNA-DNA hybridization value between the two strains was 70â% and both strains showed low levels of DNA-DNA relatedness (48-50â%) with Halobaculum gomorrense JCM 9908(T). Physiological and biochemical characteristics allowed differentiation of strains MGY-184(T) and MGY-205 from Halobaculum gomorrense JCM 9908(T). Therefore, strains MGY-184(T) and MGY-205 represent a novel species of the genus Halobaculum, for which the name Halobaculum magnesiiphilum sp. nov. is proposed; the type strain is MGY-184(T) (â=âJCM 17821(T)â=âKCTC 4100(T)).