Genome sequencing and expression of related genes of Bacillus sp. ZJS3 under As3+ stress

Abstract:

[Background] Microbial oxidation of highly toxic As³⁺ in the environment plays an important role in the biogeochemical cycle of arsenic, which has potential application value.[Objective] Bacillus sp. ZJS3 has been identified to be tolerant to As³⁺, among other heavy metals. This paper aims to clarify the morphological changes of ZJS3 in response to As³⁺stress and the genetic basis for arsenic response, which is expected to provide basic data for research on As³⁺-tolerant bacteria. [Methods] The whole genome of ZJS3 was sequenced by single-molecule real-time (SMRT) sequencing and Illumina, followed by functional annotation and bioinformatics analysis of the genes. Genes related to arsenic resistance and arsenic metabolism were analyzed by absolute quantitative PCR. [Results] The genome of ZJS3 was 5.82 Mb, which contained 1 chromosome and 3 plasmids, with GC content of 35.9%, 5 981 coding sequences (CDSs), 104 tRNA genes, 136 sRNA genes, 42 rRNA genes, 173 tandem repeats, 13 gene islands, 1 023 transporter-coding genes, 1 717 transmembrane protein-coding genes, and 160 two-component regulatory genes. A total of 97.66%, 69.30%, 78.52%, 65.49%, 67.65%, and 43.87% of the genes in the genome of ZJS3 were annotated in NR, Swiss-Prot, Pfam, COG, GO and KEGG, respectively. arsC expression was significantly higher in the arsenic treatment group than in the control group, while the level of arsB was significantly lower in the arsenic treatment group than in the control group. [Conclusion] Under As³⁺ stress, they block cell division, further influencing cell morphology. The presence of aqpZ, arsA, arsB and arsC in ZJS3 genome indicates that the strain has the ability of As³⁺ efflux and As⁵⁺ reduction, and the presence of phoUpstBACS suggests that the strain can absorb As⁵⁺. However, the expression ofarsB decreases in response to external As³⁺ stress.

Key words:As³⁺ stress;arsenic-resistant bacteria;genome sequencing;arsenic resistance gene;arsenic metabolism gene