AOB去除炔雌醇的共代谢与硝基化协同作用

采用氨氧化菌Nitrosomonas europaea降解17α-乙炔雌二醇（EE2），考察降解过程中氨氮的作用以及EE2的降解机制.结果表明，N.europaea降解EE2属于共代谢过程，氨氮是共代谢发生的必要条件.氨氧化过程产生的亚硝氮会在酸性条件下将EE2硝基化，反应符合一级动力学模型，降解速率常数与亚硝酸根、H⁺及游离亚硝酸浓度成正相关.通过控制pH值大于7.5抑制硝基化反应，证实了N.europaea对EE2的生物降解作用，生物降解反应符合一级动力学模型且降解速率常数为0.0069h^-1.当N.europaea氨氧化反应导致pH值低于7.5时，EE2的去除存在生物降解和硝基化的协同作用，EE2去除符合一级动力学模型且降解速率常数为0.0093h^-1.同时还发现一种未曾报道过的EE2生物降解产物M613，对于其雌激素效应和毒性还需进一步探究.

Synergistic effect of co-metabolism and nitration for the removal of EE2 by AOB

In this study, Nitrosomonas europaea, one type of ammonia oxidizing bacteria, was used to remove 17α-ethinylestradiol (EE2). The role of ammonia nitrogen in EE2 degradation by AOB and the degradation mechanism of EE2 were investigated. The results showed that degradation of EE2 by N. europaea was a co-metabolic process, and ammonia nitrogen was necessary for co-metabolism of EE2. The NO₂^--N produced during the ammonia oxidation process could nitrate EE2 under acidic condition. The nitration of EE2 obeyed first-order reaction kinetics and the degradation rate constants were positively correlated with the concentration of nitrite, H⁺ and FNA. The biodegradation of EE2 by N. europaea was proved by suppressing nitration of EE2 through controlling pH higher than 7.5. The co-metabolism reaction fitted first-order kinetic model with the degradation rate constant of 0.0069h^-1. Biodegradation and nitration of EE2 were synergistic for EE2 removal when pH was lower than 7.5 during ammonia oxidation process. And EE2 removal by synergistic function obeyed first-order reaction kinetics with the degradation rate constant of 0.0093h^-1. In addition, unreported EE2 biodegradation product M613 was found in this study. Its estrogen effect and toxicity need to be further investigated.