多噬伯克霍尔德氏菌WS-FJ9对草甘膦的降解特性

The characterization of glyphosate degradation by Burkholderia multivorans WS-FJ9

长期或不当施用草甘膦会对非靶标生物和环境造成破坏作用。微生物是生物修复的重要生物资源,利用微生物及其产生的降解酶处理环境中有机磷农药的方法,已显示出良好的应用前景,是近年来研究有机磷农药降解的主要发展方向。研究分离松树根际土壤的高效解磷细菌多噬伯克霍尔德氏菌(Burkholderia multivorans)WS-FJ9菌株对草甘膦的降解特性及其降解条件的优化。采用添加不同浓度草甘膦NA平板接种WS-FJ9菌株观察其对草甘膦的耐受性;分别以草甘膦为唯一碳源、氮源或磷源,探讨WS-FJ9菌株对草甘膦的利用状况;采用低进水量间歇式反应器法(FBR)测定了WS-FJ9菌株降解草甘膦动力学参数;利用Plackett-Burman(PB)、Central Composite Design(CCD)试验设计及响应面分析法(RSM)筛选与优化影响WS-FJ9菌株降解草甘膦的主要因素。WS-FJ9菌株有效降解草甘膦的最大耐受浓度为0.4%;WS-FJ9菌株在以草甘膦为唯一碳源、氮源或磷源培养基上均能正常生长;WS-FJ9菌株对草甘膦的亲和性常数(K s值)为65μL/mL,对草甘膦降解的极限浓度(S min)为21.9μL/mL;通过PB试验,筛选出3个影响菌株降解草甘膦的关键因素为培养温度、葡萄糖及硫酸铵的加入量,通过CCD设计及响应面法优化分析得到影响草甘膦降解率的关键因素的二阶模型,确定了WS-FJ9菌株降解草甘膦的最优实验操作条件为:培养温度27.7℃,葡萄糖和硫酸铵的加入量分别为0.67、0.50 g/L。实验条件下WS-FJ9菌株对草甘膦的降解率最高为72.83%。

Long-term or inappropriate use of glyphosate may damage the non-target organisms and environment. Microbes are important biological resources for bioremediation. In recent years, the method of using microbes and its catabolic enzymes to remediate organophosphorus pesticides in the environment has shown a promising potential in application. It is the main direction of research on organophosphorus pesticide degradation. This study aimed to investigate the degradation of glyphosate by an efficient phosphate solubilizing bacterium Burkholderia. multivorans WS-FJ9 which was isolated from pine rhizosphere. Strain WS-FJ9 was grown on the plates of nutrient agar （NA） with different concentrations of glyphosate to determine the tolerance of strain WS-F19 to glyphosate. Glyphosate can be used by strain WS-FJ9 as the sole sources of carbon, nitrogen and phosphorus, respectively. The degradation dynamical parameters of strain WS-FJ9 on glyphosate were determined using low flooding quantity batch reactor method （FBR）. Plackett-Burman （PB） design, central composite design （CCD）, and Response Surface Methodology （RSM） were employed to screen and optimize the main factors of strain WS-FJ9 degrading glyphosate. The maximum concentration of tolerance to glyphosate for strain WS-FJ9 to remain efficiently degrading glyphosate was 0.4%. The affinity constant （Ks） of strain WS-FJ9 to glyphosate was 65 μL/mL and the minimal concentration （Smin） of glyphosate degraded by WS-FJ9 was 21.9 μL/mL. Three key factors （cultural temperature,glucose and ammonium sulfate） for the glyphosate degradation by strain WS-FJ9 were selected using PB design. The quadratic model for the three significant factors was established using CCD design and RSM with glyphosate degradation rate as the target response. Under the optimal degradation conditions, the incubation temperature was 27.7℃, and the amount of glucose and ammonium sulfate supplemented were 9.67 g/L and 0.50 g/L, respectively. The degradation rate of glyphosate by strain WS-FJ9 reached 72.83%.