一株烟嘧磺隆高效降解菌的分离鉴定及降解特性研究

Isolation,identification and degradation characteristics of an high-efficient Nicosulfuron degrading strain

[目的]本文旨在获得烟嘧磺隆高效降解菌株来缓解玉米高粱轮作体系下烟嘧磺隆残留对后茬高粱产生的药害。[方法]从长期施用烟嘧磺隆的土壤中分离筛选出一株高效降解烟嘧磺隆的菌株DT-2,并采用单因素试验、RDA分析和响应面法对其降解特性进行研究。[结果]经形态学观察和16S rRNA鉴定为曲霉属土曲霉菌(Aspergillus terreus),该菌株培养120 h后达到最大生长量,且对100 mg·L^(-1)烟嘧磺隆的降解率高达93.87%;菌株在温度30~35℃、pH值5.0~9.0范围内可正常生长代谢,烟嘧磺隆降解率均在80%以上,可耐受并降解高达500 mg·L^(-1)的烟嘧磺隆,而菌株接种量对降解效率差异不显著;其最适生长温度和降解温度均为30℃,最佳初始底物浓度为100 mg·L^(-1),最适pH值为5,通过RDA分析得出菌株接种量对降解效率差异不显著;时间、pH值和温度是影响菌株降解率的主要因素,且影响大小为:时间>pH>温度。[结论]根据响应面法优化菌株降解烟嘧磺隆最适条件,采用Box-Behnken设计结果进行方差分析得出:在时间119 h、pH值5.8和温度30℃时,该菌株对烟嘧磺隆降解率可达98.05%,为该菌株应用于受烟嘧磺隆污染的土壤奠定理论基础。

[Objective]In order to obtain an high-efficient degradation strain of nicosulfuron to alleviate the damage caused by nicosulfuron residues to subsequent sorghum crops in maize and sorghum crop rotation systems.[Methods]A strain DT-2 was isolated and screened from the soil where nicosulfuron had been applied for a long time,Its degradation characteristics were studied by the methods of the single factor experiment,RDA analysis and response surface.[Results]The results showed that it was identified as Aspergillus terreus by morphological observation and 16S rRNA.The degradation rate of 100 mg·L^(-1)nicosulfuron was 93.87%within 120 h.The strains could grow and metabolize normally in the temperature range of 30~35℃and pH value of 5.0~9.0,the degradation rate of nicosulfuron was above 80%in all cases,it could tolerate and degrade up to 500 mg·L^(-1)of nicosulfuron,but the inoculum of the strain did not differ significantly on the degradation efficiency.The optimum growth temperature and degradation temperature were 30℃,the optimum pH value was 5,and the optimum initial substrate concentration was 100 mg·L^(-1).The RDA analysis concluded that time,pH and temperature were the main factors affecting the degradation rate of the strain,and the effect gradation was:time>pH>temperature.[Conclusion]According to the optimal conditions for the degradation of nicosulfuron by the response surface method,and the analysis of variance used by Box-Behnken design showed that the degradation rate of nicosulfuron by the strain could reach 98.05%at 119 h,pH 5.8 and temperature 30℃,which laid a theoretical foundation for the application of this strain to soil contaminated with nicosulfuron.