多氯联苯降解菌的选育及降解性能研究

Isolation and characterization of polychlorinated biphenyl-degrading bacterium

从长期受PCBs污染的土壤中筛选出2株多氯联苯降解菌,并对其形态和生物学特性进行了观察研究。通过对这2株菌的驯化筛选,得到混菌对PCBs的降解效果最好。通过改变菌株的降解条件(pH、温度、接菌量及装液量)可知,混菌的最佳降解pH值为7.0、温度为30℃、接菌量为OD600nm=1.0的菌液2 mL、装液量为10.00 mL。在上述最佳条件下,混菌对10 mg/L的PCBs降解15 d,去除率可达70%左右。通过表面活性剂的增效降解作用研究可知,混合表面活性剂表现为低浓度(<500 mg/L)促进混菌对PCBs的降解,高浓度(>700 mg/L)抑制混菌对PCBs的降解。在降解体系中添加300 mg/L的混合表面活性剂,经16 d的降解,可以将PCBs降解率提高到91.5%。

Two polychlorinated biphenyls-degrading bacteria were isolated from long-term PCBs-contaminated soil using biphenyl as carbon source and energy source. These halophilic bacterial strains were separated, purified and enriched. After morphological observation and dye identification, the mixed fermentation was selected for the experiments about influence on degrading polychalorinated biphenyls at last. The optimal experimental conditions of PCBs-degrading were obtained according to the changes of pH, temperature, inoculation amount and liquid medium. The results indicated that the degradation ratio could reach to 70% when the temperature was 30 ℃, pH was7.0, inoculation amount was OD600nm =1.0, and liquid medium was 10.00 mL. Results from surfactants efficiency degradation proved that the mixed surfactants in low concentrations（〈500 mg/L） could promote the degradation and high concentrations（〉700 mg/L） could suppress the degradation. The degradation ratio could reach to 91.5% after 16 d when mixed surfactants（300 mg/L） were added to the degradation system.