Abstract: In this study, sediment samples were collected from the West Taijiner salt Lake in the Qaidam Basin for enrichment, culture, isolation and purification of salt-tolerant microorganisms, and the salt tolerance ability of the strains was tested and whole genome sequence was carried out. Genes and pathways related to salt tolerance in the genome were excavated. A strain of salt-tolerant bacterium was isolated and blasted having 99.79% similarity with Bacillus atrophaeus according to 16S rRNA gene sequence analysis. It was named as Bacillus atrophaeus W-4. The growth curves of W-4 were measured under different NaCl mass concentration gradients to explore its tolerance to NaCl, and the results showed that the strain W-4 could tolerate up to 0.25 kg/L NaCl. It was a moderately halotolerant bacterium. Genome sequence analysis showed that W-4 contained one chromosomal genome with a size of 4284607 bp. According to the annotation analysis of KEGG database, it was found that there were a variety of genes that might be related to NaCl tolerance in the genome of strain W-4, including 5 genes related to Na⁺ transporter, 7 genes related to K⁺ transporter, 37 genes associated with compatibility solutes, and 5 genes associated with chaperones. The results indicated that strain W-4 had the potential to adapt to high-salt environment at the genetic level, and this study will provide a theoretical basis for the application of the salt-tolerant strain.

Key words: extreme environment, salt lake microorganisms;Bacillus, whole genome sequencing, salt tolerance genes