State Key Joint Laboratory of Environmental Simulation and Pollution Control, College of Environmental Sciences and Engineering, Peking University, Beijing 100871, China.
State Key Joint Laboratory of Environmental Simulation and Pollution Control, College of Environmental Sciences and Engineering, Peking University, Beijing 100871, China; South China Institute of Environmental Science, Ministry of Ecology and Environment, Guangzhou 510535, China.
Sci Total Environ. 2022 Nov 20;848:157570. doi: 10.1016/j.scitotenv.2022.157570. Epub 2022 Jul 27.
Methanogenesis is a key process in carbon cycling in lacustrine ecosystems. Knowledge of the methanogenic pathway is important for creating mechanistic models as well as predicting methane emissions. Due to low concentrations of methyl substrates in freshwater lakes, the proportion of methylotrophic methanogenesis is believed to be negligible in such environments. However, the high abundance of methylotrophic methanogens previously detected in Dianchi Lake suggests that methylotrophic methanogenesis may be underestimated in eutrophic lakes, whereas their influencing factors and mechanisms are not yet clear. In this study, the effects of cyanobacteria biomass (CB) or/and nitrate nitrogen on methanogenesis, especially methylotrophic pathway, in eutrophic lakes were investigated using microcosm simulation experiments combined with chemical analysis and high-throughput sequencing techniques. The results showed that either CB or nitrate nitrogen had significant effects on methane flux, the archaeal diversity and community structure of methanogens. Functional prediction, together with the result of chemical analysis, revealed that CB could promote methylotrophic methanogenesis by providing methyl organic substrates, while nitrate nitrogen increased the relative abundance of obligate methylotrophic methanogens by competitively inhibiting the other two methanogenic pathways. In eutrophic lake where both CB and nitrate present at a high concentration, methylotrophic methanogenesis could play a much more important role than previously believed.
产甲烷作用是湖泊生态系统碳循环中的一个关键过程。了解产甲烷途径对于创建机制模型以及预测甲烷排放都很重要。由于在淡水湖中甲基供体的浓度较低，因此在这种环境中，认为依赖甲基的产甲烷作用的比例可以忽略不计。然而，先前在滇池中检测到的大量依赖甲基的产甲烷菌表明，在富营养化湖泊中，依赖甲基的产甲烷作用可能被低估了，而其影响因素和机制尚不清楚。在这项研究中，采用微宇宙模拟实验结合化学分析和高通量测序技术，研究了富营养化湖泊中蓝藻生物量（CB）或/和硝酸盐氮对产甲烷作用，特别是依赖甲基的途径的影响。结果表明，无论是 CB 还是硝酸盐氮都对甲烷通量、产甲烷菌的古菌多样性和群落结构有显著影响。功能预测，结合化学分析的结果，表明 CB 可以通过提供甲基有机底物来促进依赖甲基的产甲烷作用，而硝酸盐氮通过竞争抑制其他两种产甲烷途径来增加专性依赖甲基的产甲烷菌的相对丰度。在 CB 和硝酸盐都以高浓度存在的富营养化湖泊中，依赖甲基的产甲烷作用可能比以前认为的更为重要。
