Cometabolic biotransformation and microbial-mediated abiotic transformation of sulfonamides by three ammonia oxidizers
Cometabolic biotransformation and microbial-mediated abiotic transformation of sulfonamides by three ammonia oxidizers
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三种氨氧化剂对磺胺类药物的共代谢生物转化和微生物介导的非生物转化
DOI：
10.1016/j.watres.2019.05.031
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发表时间：
2019
期刊：
影响因子：
12.8
通讯作者：
Wu Qinglong L.
中科院分区：
文献类型：
--
作者：
Zhou Li-Jun;Han Ping;Yu Yaochun;Wang Baozhan;Men Yujie;Wagner Michael;Wu Qinglong L.
研究了3种遗传距离较远的氨氧化菌对7种磺胺类化合物的生物转化能力，它们分别是氨氧化古菌（AOA）、氨氧化细菌（AOB）和完全氨氧化菌（comammox）Nitrospirainopinata。去除率和蛋白质标准化生物转化速率常数表明，AOA菌株N. gargensis抑制SA生物转化速率最高，其次是N. inopinata和N. nitrosaNm 90.对磺胺嘧啶（SDZ）、磺胺二甲嘧啶（SMZ）和磺胺甲恶唑（SMX）的生物转化产物及其转化机制进行了研究。通过对TP分子式和近似结构的分析，发现AOA菌株在生物转化过程中进行了SA脱氨基、羟基化和硝化反应; AOB菌株主要进行SA脱氨基反应; comammox菌株仅参与脱氨基反应。脱氨反应由脱氨酶催化，而羟基化和硝化反应则由氨单加氧酶（AMO）的非特异性活性介导。此外，证明了在三种氨氧化剂中，只有AOB有助于蝶呤-SA缀合物的形成。SDZ、SMZ和SMX的生物转化仅在氨氧化活跃时发生，表明其转化机制为共代谢。有趣的是，SA也可以被羟胺转化，羟胺是氨氧化的中间体，这表明除了酶促转化之外，微生物诱导的非生物机制有助于氨氧化过程中的SA转化。总的来说，使用纯培养物的实验，本研究提供了重要的见解氨氧化剂在SA生物转化中发挥的作用。
The abilities of three phylogenetically distant ammonia oxidizers,Nitrososphaera gargensis, an ammonia-oxidizing archaeon (AOA);Nitrosomomas nitrosaNm90, an ammonia-oxidizing bacterium (AOB); and Nitrospirainopinata, the only complete ammonia oxidizer (comammox) available as a pure culture, to biotransform seven sulfonamides (SAs) were investigated. The removals and protein-normalized biotransformation rate constants indicated that the AOA strainN. gargensisexhibited the highest SA biotransformation rates, followed byN. inopinataandN. nitrosaNm90. The transformation products (TPs) of sulfadiazine (SDZ), sulfamethazine (SMZ) and sulfamethoxazole (SMX) and the biotransformation mechanisms were evaluated. Based on the analysis of the TP formulas and approximate structures, it was found that during biotransformation, i) the AOA strain carried out SA deamination, hydroxylation, and nitration; ii) the AOB strain mainly performed SA deamination; and iii) the comammox isolate participated only in deamination reactions. It is proposed that deamination was catalyzed by deaminases while hydroxylation and nitration were mediated by nonspecific activities of the ammonia monooxygenase (AMO). Additionally, it was demonstrated that among the three ammonia oxidizers, only AOB contributed to the formation of pterin-SA conjugates. The biotransformation of SDZ, SMZ and SMX occurred only when ammonia oxidation was active, suggesting a cometabolic transformation mechanism. Interestingly, SAs could also be transformed by hydroxylamine, an intermediate of ammonia oxidation, suggesting that in addition to enzymatic conversions, a microbially induced abiotic mechanism contributes to SA transformation during ammonia oxidation. Overall, using experiments with pure cultures, this study provides important insights into the roles played by ammonia oxidizers in SA biotransformation.