扑草净的微生物降解及菌剂性能分析

Analysis of microbial degradation of prometryn and inoculum performance

[目的]降低土壤中农药残留,提升农产品安全性。[方法]采用平板划线法从实验室的菌种资源中筛选能以扑草净作为营养物质生长的降解菌株;利用分光光度法和液相色谱法测定菌株的生长情况及扑草净降解率,通过单因素实验和响应曲面法优化3株菌的降解条件以进一步提高菌株的扑草净降解率。使用海藻酸钠及壳聚糖作为载体材料制备菌剂,并测试其对温度、pH及紫外线的耐受能力。[结果]获得3株可高效降解扑草净的菌株Shinella sp.(P-7)、Herbaspirillum sp.(P-12)和Pseudomonas sp.(P-13),对100 mg/L扑草净的降解率分别为80.93%、76.87%、85.06%,均超过75%;经优化,在扑草净质量浓度100 mg/L、培养7 d时:菌株P-13的降解率达到88.12%,菌株P-7、P-12的降解率提高至82.96%、79.04%。海藻酸钠-壳聚糖微囊法制得的固定化小球传质性能及机械强度佳,扑草净降解效果优良,环境耐受度较强。[结论]3株降解菌的获得为环境中扑草净的降解扩充了微生物资源,并利用固定化技术提高了菌株的耐冷性、pH稳定性及紫外耐受度,为扑草净的实际修复应用提供了可行性依据。

[Aims] This study aims to reduce pesticide residues in the soil and improve the safety of agricultural products. [Methods] A plate scribing method was used to select degrading strains which grew with prometryn as the nutrient from laboratory. The growth and degradation rate of strains were monitored by spectrophotometry and liquid chromatography. The degradation conditions of the 3 strains were optimized by single-factor experiments and response surface methodology to further improve the degradation rate of them. Immobilized bacterial agents were prepared using sodium alginate and chitosan as carrier materials and tested for their tolerance to temperature, pH and UV light.[Results] 3 Strains of Shinella sp.(P-7), Herbaspirillum sp.(P-12) and Pseudomonas sp.(P-13) were obtained for the efficient degradation of prometryn. The degradation rates was 80.93%, 76.87% and 85.06%(all above 75%), at the concentration of 100 mg/L. The degradation rate of strain P-13 reached 88.12%, and the degradation rate of strains P-7and P-12 increased to 82.96% and 79.04%, respectively, at a prometryn concentration of 100 mg/L and incubation time of 7 d. The microencapsulation method of sodium alginate-chitosan produced good mass transfer and mechanical strength, and the degradation effect of prometryn and environmental tolerance was excellent. [Conclusions] The acquisition of the 3 strains has expanded new microbial resources for the degradation of prometryn in the environment. The immobilization technology was also used to improve the cold resistance, pH stability and UV tolerance of the 3 strains,providing a feasibility basis for the practical remediation application of prometryn.