污水厂中草甘膦降解菌的筛选及其降解特性研究

Screening of Glyphosate Degrading Bacteria in Wastewater Treatment Plant and Study on Their Degradation Characteristics

为解决农业生产中草甘膦污染水体问题,本文通过利用草甘膦为唯一碳源,从污水厂活性污泥中分离、纯化、培养,筛选出降解草甘膦能力较强的菌株PP84,通过观察形态和16S r DNA序列鉴定为巨大芽孢杆菌(Bacillus megaterium),试验研究了菌株对草甘膦的降解特性和影响因素。结果表明,Bacillus megaterium菌株在草甘膦浓度为500 mmol/L的培养基中,48 h内对草甘膦的降解率可达54.67%,生长范围宽泛,最适合生长的环境为pH 6.0。在重金属毒性实验中发现,当环境中Cu^(2+)浓度在50 mg/kg,对巨大芽孢杆菌降解草甘膦有一定的毒害作用,降解率为65.6%,当Cu^(2+)浓度为250 mg/kg时对菌株的生长极其不利,对草甘膦的降解率降为37.9%;环境中Cd^(2+)浓度为0.25 mg/kg和2.5 mg/kg时对巨大芽孢杆菌降解草甘膦都有一定的抑制作用,菌株对草甘膦的降解率分别只有50.4%、28.8%。

To solve the problem of glyphosate pollution of water body in agricultural production,this paper reported a strain with strong degradation ability of glyphosate,Bacillus megaterium,which was isolated from sewage plant activated sludge,and studied its growth curve and glyphosate degradation ability.Results showed that the glyphosate degradation rate within 48 h was up to 54.67%by Bacillus megaterium grown in 500 mmol/L glyphosate medium.Bacillus megaterium could grow in a broad range of p H with the most suitable growth p H value of 6.0.In heavy metal toxicity test,Cu^(2+) concentration of 50 mg/kg in the environment was disadvantageous to the degradation of glyphosate by Bacillus megaterium,and the degradation rate was 65.6%,while the Cu^(2+) concentration of 250mg/kg could reduce the degradation rate to 37.9%;Cd^(2+) concentration of 0.25 mg/kg and 2.5 mg/kg could inhibit the degradation rate of Bacillus megaterium to 50.4%and 28.8%,respectively.