School of Environmental Science and Engineering, Shandong University, Jinan 250100, China; School of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta, GA 30332, United States.
School of Environmental Science and Engineering, Shandong University, Jinan 250100, China.
Sci Total Environ. 2019 Jan 15;648:916-922. doi: 10.1016/j.scitotenv.2018.08.185. Epub 2018 Aug 17.
Anaerobic oxidation of methane (AOM) coupled to denitrification is becoming the focus of scientific inquiry due to its potential contribution to global carbon and nitrogen cycles. AOM has been previously reported to proceed with nitrate (NO) or nitrite (NO). However, little research has been conducted on the simultaneous use of methane (CH) and nitrous oxide (NO). Here, coupled CH and NO biotransformation in a freshwater wetland sediment was obtained in a 7-day anaerobic sediment incubation assay. The significant CO accumulation and decrease of CH emission in sediment microcosms was attributed to two mechanisms: inhibition of methanogenesis and NO-dependent AOM. To further confirm the coupled CH and NO transformation, a C-labelled stable isotope tracer assay after anaerobic incubation was conducted with NO and/or CH amendments. The NO-dependent AOM rate was 3.41 ± 0.13 nmol CO g dry sediment·day. According to metagenomic analysis, addition of NO stimulated AOM by increasing the activity and abundance of methanotrophic bacteria and by increasing enzymatic activities in the electron transport chain. Based on these results, we propose coupled CH and NO biotransformation in the sediment microcosms for the first time, carried out by unidentified methanotroph(s) via intra‑oxygen produced in the presence of NO. Such a process has the potential to reduce the emission of two highly potent greenhouse gases and makes a significant contribution to the link of global carbon and nitrogen cycles in anoxic environments.
由于其对全球碳氮循环的潜在贡献，甲烷（AOM）的厌氧氧化与反硝化耦联正成为科学研究的焦点。先前已有研究报道，AOM 可与硝酸盐（NO ）或亚硝酸盐（NO ）反应。然而，对于甲烷（CH ）和一氧化二氮（NO ）的同时使用，研究甚少。在这里，在为期 7 天的厌氧沉积物培养实验中，在淡水湿地沉积物中获得了耦合的 CH 和 NO 生物转化。在沉积物微宇宙中，显著的 CO 积累和 CH 排放减少归因于两种机制：产甲烷作用的抑制和依赖 NO 的 AOM。为了进一步证实耦合的 CH 和 NO 转化，在厌氧孵育后进行了 C 标记稳定同位素示踪剂实验，添加了 NO 和/或 CH 。NO 依赖的 AOM 速率为 3.41±0.13 nmol CO g 干沉积物·天。根据宏基因组分析，添加 NO 通过增加甲烷氧化菌的活性和丰度以及增加电子传递链中的酶活性来刺激 AOM。基于这些结果，我们首次提出了沉积物微宇宙中 CH 和 NO 的耦合生物转化，由在存在 NO 的情况下产生的内氧的未鉴定甲烷氧化菌（s）进行。这种过程有可能减少两种高潜力温室气体的排放，并为缺氧环境中全球碳氮循环的联系做出重大贡献。
