Yu Lei, Ju Cheng-Jia, Jing Kai-Yan, Wang Zi-Yang, Niyazi Shareen, Wang Quan
Department of Environmental Engineering, College of Biology and the Environment, Nanjing Forestry University, Nanjing, 210037, China; College of Biology and the Environment, Co-Innovation Center for Sustainable Forestry in Southern China, Nanjing Forestry University, Nanjing, 210037, China.
Department of Environmental Engineering, College of Biology and the Environment, Nanjing Forestry University, Nanjing, 210037, China.
J Environ Manage. 2023 May 1;333:117455. doi: 10.1016/j.jenvman.2023.117455. Epub 2023 Feb 7.
To improve the electron (e) transfer efficiency, exogenous redox mediators (RMs) were usually employed to enhance the denitrification efficiency due to the electron shuttling. Previous studies were mainly focused on how to improve the extracellular electron transfer (EET) by exogenous RMs. However, the intracellular electron transfer (IET), another crucial e transfer pathway, of biological denitrification was scarcely reported, especially for the relationship between the denitrification and IET. In this study, Coenzyme Q, Complexes I, II and III were determined as the core components in the IET chain of denitrification by using four specific respiration chain inhibitors (RCIs). Anthraquinone-2-sulfonate (AQS) partially recovered the IET of denitrification from NO-N to N gas when the RCIs were added. Specifically, the generations of N gas were improved by 9.68%-18.25% in the experiments with RCIs and AQS, comparing to that with RCIs. nrfA gene was not detected by reverse transcription-polymerase chain reaction, suggesting that Klebsiella oxytoca strain could not conduct dissimilatory nitrate reduction to ammonium. Nitrate assimilation was considered as the main NH-N formation way of K. oxytoca strain. The two e transfer pathways of denitrification were constructed and the roles of AQS on the IET and EET of denitrification were specifically discussed. The results of this study provided a better understanding of the e transfer pathways of denitrification, and suggested a potential practical use of exogenous RM on bio-treatment of nitrate-containing wastewater.
为提高电子（e）转移效率，由于电子穿梭作用，通常采用外源性氧化还原介质（RMs）来提高反硝化效率。以往的研究主要集中在外源性RMs如何改善细胞外电子转移（EET）。然而，生物反硝化的另一个关键电子转移途径——细胞内电子转移（IET）却鲜有报道，尤其是反硝化与IET之间的关系。在本研究中，通过使用四种特异性呼吸链抑制剂（RCIs），确定辅酶Q、复合物I、II和III为反硝化IET链中的核心成分。当添加RCIs时，蒽醌-2-磺酸盐（AQS）部分恢复了反硝化从NO-N到N气体的IET。具体而言，与仅添加RCIs的实验相比，在添加RCIs和AQS的实验中，N气体的生成量提高了9.68%-18.25%。通过逆转录-聚合酶链反应未检测到nrfA基因，表明产酸克雷伯菌不能进行异化硝酸盐还原为铵。硝酸盐同化被认为是产酸克雷伯菌菌株形成NH-N的主要途径。构建了反硝化的两条电子转移途径，并具体讨论了AQS对反硝化IET和EET的作用。本研究结果有助于更好地理解反硝化的电子转移途径，并提示外源性RM在含硝酸盐废水生物处理中的潜在实际应用。
