Yu Yaochun, Han Ping, Zhou Li-Jun, Li Zhong, Wagner Michael, Men Yujie
Department of Civil and Environmental Engineering , University of Illinois at Urbana-Champaign , Urbana , Illinois 61801-2352 , United States.
Department of Microbiology and Ecosystem Science, Division of Microbial Ecology, Research Network "Chemistry meets Microbiology" , University of Vienna , 1090 Vienna , Austria.
Environ Sci Technol. 2018 Aug 21;52(16):9196-9205. doi: 10.1021/acs.est.8b02801. Epub 2018 Jul 30.
Biotransformation of various micropollutants (MPs) has been found to be positively correlated with nitrification in activated sludge communities. To further elucidate the roles played by ammonia-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB), we investigated the biotransformation capabilities of an NOB pure culture ( Nitrobacter sp.) and an AOB ( Nitrosomonas europaea)/NOB ( Nitrobacter sp.) coculture for 15 MPs, whose biotransformation was reported previously to be associated with nitrification. The NOB pure culture did not biotransform any investigated MP, whereas the AOB/NOB coculture was capable of biotransforming six MPs (i.e., asulam, bezafibrate, fenhexamid, furosemide, indomethacin, and rufinamide). Transformation products (TPs) were identified, and tentative structures were proposed. Inhibition studies with octyne, an ammonia monooxygenase (AMO) inhibitor, suggested that AMO was the responsible enzyme for MP transformation that occurred cometabolically. For the first time, hydroxylamine, a key intermediate of all aerobic ammonia oxidizers, was found to react with several MPs at concentrations typically occurring in AOB batch cultures. All of these MPs were also biotransformed by the AOB/NOB coculture. Moreover, the same asulam TPs were detected in both biotransformation and hydroxylamine-treated abiotic transformation experiments, whereas rufinamide TPs formed from biological transformation were not detected during hydroxylamine-mediated abiotic transformation, which was consistent with the inability of rufinamide abiotic transformation by hydroxylamine. Thus, in addition to cometabolism likely carried out by AMO, an abiotic transformation route indirectly mediated by AMO might also contribute to MP biotransformation by AOB.
已发现各种微污染物（MPs）的生物转化与活性污泥群落中的硝化作用呈正相关。为了进一步阐明氨氧化细菌（AOB）和亚硝酸盐氧化细菌（NOB）所起的作用，我们研究了一种NOB纯培养物（硝化杆菌属）以及一种AOB（欧洲亚硝化单胞菌）/NOB（硝化杆菌属）共培养物对15种MPs的生物转化能力，先前报道这些MPs的生物转化与硝化作用有关。NOB纯培养物不能对任何所研究的MP进行生物转化，而AOB/NOB共培养物能够对6种MPs（即杀草强、苯扎贝特、环酰菌胺、呋塞米、吲哚美辛和鲁非酰胺）进行生物转化。鉴定了转化产物（TPs）并提出了暂定结构。用氨单加氧酶（AMO）抑制剂辛炔进行的抑制研究表明，AMO是负责共代谢发生的MP转化的酶。首次发现，羟胺作为所有好氧氨氧化菌的关键中间体，在AOB分批培养中通常出现的浓度下能与几种MPs发生反应。所有这些MPs也都能被AOB/NOB共培养物生物转化。此外，在生物转化和羟胺处理的非生物转化实验中都检测到了相同的杀草强TPs，而在羟胺介导的非生物转化过程中未检测到由生物转化形成的鲁非酰胺TPs，这与羟胺无法对鲁非酰胺进行非生物转化一致。因此，除了可能由AMO进行的共代谢外，由AMO间接介导的非生物转化途径也可能有助于AOB对MP的生物转化。
