Isolation and identification of sulfate-reducing bacteria in goaf water in Yangquan of Shanxi Province and domestication for the reduction

Abstract:

[Background] Surface water/ground water flows back to the goaf of sulfur-containing coal mine, forming the acidic goaf water. The water, with high salinity and sulfate content, threatens ecosystem health. Microorganisms, which feature low cost and environmental protection, has promising prospect of application in the treatment of goaf water. However, the currently available sulfate-reducing bacteria (SRB) are only highly active under suitable temperature and neutral pH, and are intolerant to low temperature and acidic conditions in northern China. [Objective] To isolate SRB from goaf water in Shandi River Basin of Yangquan, Shanxi, and to domesticate them so that they can tolerate the low temperature and acidic condition and be used for the treatment of goaf water in northern China. [Methods] Microorganisms in goaf water sample from Shandi River Basin were enriched and SRB were isolated. Then the SRB were characterized by Gram staining and scanning electron microscopy and identified based on 16S rRNA sequence alignment. Their growth characteristics and sulfate-reducing capacity were also investigated. On this basis, temperature and pH were lowered to domesticate the efficient SRB, thereby exploring their potential in the treatment of goaf water. [Results] Two strains of SRB, YQ-1 and YQ-2, were isolated, belonging to the Gram-negative Proteiniclasticum and Desulfovibrio, respectively. At 30 ℃ and pH 7.5, YQ-1 and YQ-2 reduced 96.75% and 75.48% of the 1 100 mg/L sulfate, respectively. The highly efficient strain YQ-1 was selected for domestication at low temperature and pH. The sulfate removal rate of the strain was 91.49% at 15 ℃ and pH 7.5 after low-temperature domestication, 85.69% higher than that before domestication. The removal rate was up to 37.21% at 15 ℃ and pH 4.5 after low-pH domestication, which was 34.30% higher than that before domestication. [Conclusion] The tolerance of YQ-1 to low temperature and low pH was improved, and the efficiency of sulfate reduction was also enhanced after domestication. This work provided strain resources and theoretical basis for the treatment of goaf water in northern China.