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Title:Ammonia-monooxygenase-mediated cometabolic biotransformation and abiotic transformation of micropollutants
Author(s):Yu, Yaochun
Advisor(s):Men, Yujie
Department / Program:Civil & Environmental Eng
Discipline:Environ Engr in Civil Engr
Degree Granting Institution:University of Illinois at Urbana-Champaign
Subject(s):Ammonia monooxygenase
Abiotic transformation
Abstract:Biotransformation of a number of micropollutants (MPs) has been found to positively correlate with nitrification activities in inhibition studies of nitrifying activated sludge communities. To further elucidate roles played by ammonia-oxidizing bacteria (AOB), and nitrite-oxidizing bacteria (NOB) that grow dependently on AOB, we investigated the biotransformation capabilities of an NOB pure culture (Nitrobacter sp.), and an AOB (Nitrosomonas europaea)/NOB co-culture for fifteen MPs, whose biotransformation were associated with nitrification activities. The NOB did not biotransform any MP investigated, whereas the AOB/NOB co-culture was capable of biotransforming asulam, and five other MPs. Asulam biotransformation occurred via co-metabolism. Two transformation products of asulam (TP230 and TP274) were identified by suspect screening and nontarget screening. The tentative TP structures were proposed based on MS2 spectra. Ammonia monooxygenase (AMO) was the responsible enzyme, given the competitive inhibition of asulam on AMO, and the instantaneous cease of asulam biotransformation when AMO was inhibited by octyne. More interestingly, hydroxylamine, the product of ammonia oxidization by AMO was found to react with several MPs, most of which were also biotransformed by the AOB/NOB co-culture. Moreover, TP230 and TP 274 could also be detected in hydroxylamine added abiotic samples. Thus, in addition to cometabolism carried out directly by AMO, an abiotic transformation route indirectly mediated by AMO might also present during MP biotransformation. Taken together, this study advances fundamental knowledge of roles played by specific nitrifying microbial groups in MP biotransformation, as well as the underlying mechanisms. Findings also provide important insights into engineering applications for MP removal.
Issue Date:2017-11-13
Rights Information:Copyright 2017 Yaochun Yu
Date Available in IDEALS:2018-03-13
Date Deposited:2017-12

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