2株分别降解壬基酚和双酚A细菌的分离、鉴定和降解特性

对上海天山污水处理厂氧化沟的活性污泥进行驯化,分离纯化并筛选得到2株能分别以壬基酚（NP）和双酚A（BPA）为唯一碳源和能源生长的降解菌株N1和B2.根据菌株的16S rDNA序列同源性分析,结合菌落和菌体形态以及生理生化特征,初步鉴定N1为柠檬酸杆菌属（Citrobacter sp.57）,B2为芽孢杆菌属（Bacillus sp.A1-3）.通过摇瓶试验并借助正交试验优化菌株降解条件,结果表明,N1降解NP的最佳条件:35 ℃,初始pH为 5.5,无机盐培养液中初始ρ（NP）为10 　mg/L,降解24 h,去除率达79.64%；B2降解BPA的最优条件:30 ℃,初始pH为 7.0,无机盐培养液中初始ρ（BPA）为10 　mg/L,降解24 h,去除率达78.68%.在该优化温度和初始pH条件下,分别在不同初始ρ（NP）和ρ（BPA）下对N1和B2降解反应过程进行动力学分析,该降解过程在底物质量浓度为5～40 　mg/L时符合Monod方程,N1和B2的动力学参数K_s和μ_m分别为4.32,8.36和0.177 8,0.111 9. 

Isolation,Identification and Degradation Characteristics of Two Bacterial Strains Degrading NP and BPA

Two bacterial strains designated as N1 and B2,which can respectively use NP and BPA as the sole carbon and energy source,were isolated,purified and sorted from acclimated activated sludge collected from the oxidation ditch of the Shanghai Tianshan Wastewater Treatment Plant.Strain N1 and B2 were identified preliminarily as Citrobacter sp. 57 and Bacillus sp. A1-3,respectively,according to their sequence analysis of 16S rDNA as well as morphological,physiological and biochemical characteristics.The degrading conditions for strain N1 and B2 were optimized by tests in shaking flasks and orthogonal tests.The results showed that the optimal conditions for the degradation of NP by strain N1 were 35 ℃,initial pH 5.5,and initial NP concentration 10 　mg/L in mineral salt medium,with a degradation rate of 79.64% in 24 h; the optimal conditions for the degradation of BPA by strain B2 were 30 ℃,initial pH 7.0,and initial BPA concentration 10 　mg/L in mineral salt medium,with a degradation rate of 78.68% in 24 h.Based on the above optimal temperature and initial pH,kinetics analysis of the degradation of NP and BPA by strain N1 and B2 under different initial NP and BPA concentrations showed that the degradation reaction conformed to the Monod equation when the initial substrate concentrations were in the range of 5-40 　mg/L,with the kinetic parameters K_s and μ_m being 4.32,8.36 and 　0.1778,0.1119,respectively.