Polyphasic Taxonomy And Genomic Studies Of Halophilic Microorganism In Salt Mines Of Aksu Prefecture, Xinjiang Province

Halophilic microorganisms can grow well at more than 0.2 M NaCl concentration. They can adapt diverse salt environments with salt concentration from low to high, and even saturated, such as marine, salt lakes, salt mines, solar saltern, salt soil and pickled food.The salt mines of Aksu prefecture, Xinjiang province, are especially ancient with dreadful environment, such as dry climate, large temperature difference between day and night, lacking nutrition etc. The halophilic microorganisms should own the special mechanism of adaption to survive in such extreme environment, such as the tolerance of ultraviolet radiation, high salt concentration and drought. The resource of halophilic microorganisms in salt mines of Aksu prefecture is lacked to be investigated, especially the resource of halophilic archaea. Through investigation, we can explore novel species, and we also can sequence and analyze the characteristic microbes to explore new genes, as well as the tolerant mechanism to adapt the extreme environment. It is helpful for providing the materials and references to study the halophilic microbes, and significant to study the origin and evolution of life.The research mainly studying the salt mines of Aksu prefecture, Xinjiang province, including salt mine samples from Wensu county, Kuche county and Baicheng county. By using cultivation-dependent technique to isolate the microbes, we obtained various halophilic bacteria and halophilic archaea, including many novel species. According to the principle of polyphasic taxonomy, phenotypic, chemotaxonomic and genotypic characteristics were combined to determine the taxonomy of five new strains. Four novel halophilic archaea species (Halolamina salifodinae WSY15-H1T, Halolamina salina WSY15-H3T, Halopiger salifodinae KCY07-B2T and Halopelagius longus BC12-B1T) and two novel moderate halophilic bacteria species (Aquibacillus salifodinae WSY08-1T and Bacillus salitolerans KC1T) were proposed. Up to date, the genus Halolamina contains four species, the genus Halopiger contains three species, the genus Halopelagius contains three species, the genus Aquibacillus contains four species, and the genus Bacillus contains more than 200 species. So we could conclude this study enriched the resource of halophiles, which could be used as the material on related researches.The halophilic archaeon Hpg. salifodinae KCY07-B2T, which was isolated from Kuche county salt mine sample, was selected to be genome sequenced and analyzed. The draft genome sequence was composed of 81 scaffolds for 4.35 Mb with 65.41% G+C content and contained 4,254 predicted genes, including 4,204 protein-coding genes,45 tRNA genes,1 16S rRNA gene,2 23S rRNA genes and 2 5S rRNA genes. The analysis of the genome sequence focused on the adaption mechanism of the halophilic archaea in the oligotrophic, high ultraviolet radiation and hypersaline environment. The Genomic data showed strain Hpg. salifodinae KCY07-B2T might own various mechanisms to adapt the extreme environment. It had two strategies to resist osmotic stress. It could uptake and synthesize compatible solutes glycine betaine, and contained many genes related K+ and Na+ transport systems. In addition, the genome contained many genes encoding proteins for various DNA repair systems to resist the UV radiation in its habitat. All information mentioned above revealed how strain Hpg. salifodinae KCY07-B2T colud survive in the environment of salt mine.