Halobaculum halophilum sp. nov. and Halobaculum salinum sp. nov., isolated from salt lake and saline soil

Abstract

Two halophilic archaeal strains, Gai3-2T and NJ-3-1T, were isolated from salt lake and saline soil samples, respectively, collected in PR China. The 16S rRNA gene sequences of the two strains were 97.5% similar to each other. Strains Gai3-2T and NJ-3-1T had the highest sequence similarities to ‘ Halobonum tyrrellense ’ G22 (96.7 and 97.8%, respectively), and displayed similarities of 91.5–93.5% and 92.3–94.7%, respectively, to Halobaculum members. Phylogenetic analysis revealed that the two strains formed different branches and clustered tightly with ‘ H. tyrrellense ’ G22 and Halobaculum members. The average nucleotide identity (ANI), in silico DNA–DNA hybridization (isDDH) and amino acid identity (AAI) values between the two strains were 83.1, 26.9 and 77.9%, respectively, much lower than the threshold values proposed as a species boundary. These values between the two strains and ‘ H. tyrrellense ’ G22 (ANI 77.9–78.2%, isDDH 22.5–22.6% and AAI 68.8–69.3%) and Halobaculum members (ANI 77.53–77.63%, isDDH 21.8–22.3% and AAI 68.4–69.4%) were almost identical, and much lower than the recommended threshold values for species delimitation. These results suggested that strains Gai3-2T and NJ-3-1T represent two novel species of Halobaculum . Based on phenotypic, chemotaxonomic and phylogenetic properties, strains Gai3-2T (=CGMCC 1.16080T=JCM 33550T) and NJ-3-1T (=CGMCC 1.16040T=JCM 33552T) represent two novel species of the genus Halobaculum , for which the name Halobaculum halophilum sp. nov. and Halobaculum salinum sp. nov. are proposed.