Abstract：
The greenhouse gas methane in soils has been considered to be consumed mainly by aerobic methane-oxidizing bacteria for a long time. In the last decades, the discovery of anaerobic methanotrophs greatly complemented the methane cycle, but their contribution rates and ecological significance in soils remain undescribed. In this work, the soil samples from forest, grassland and cropland in four different climatic regions were collected to investigate these conventional and novel methanotrophs. A dual-core microbial methane sink, responsible for over 80 % of soil methane emission reduction, was unveiled. The aerobic core was performed by aerobic methanotrophic bacteria in topsoil, who played important roles in stabilizing bacterial communities. The anaerobic core was denitrifying methanotrophs in anoxic soils, including denitrifying methanotrophic bacteria from NC10 phylum and denitrifying methanotrophic archaea from ANME-2d clade. They were ubiquitous in terrestrial soils and potentially led to around 50 % of the total methane removal. Human activities such as livestock farming and rice cultivation further promoted the contribution rates of these denitrifying methanotrophs. This work elucidated the emission reduction contribution of different methanotrophs in the continental setting, which would help to reduce uncertainties in the estimations of the soil methane emission.
摘要：
长期以来，土壤中的温室气体甲烷主要被好氧甲烷氧化细菌消耗。在过去的几十年里，厌氧甲烷生物的发现极大地补充了甲烷循环，但它们在土壤中的贡献率和生态意义仍未描述。在这项工作中,来自森林的土壤样本，收集了四个不同气候区的草地和农田，以调查这些常规和新型甲烷氧化菌。双核微生物甲烷汇,负责80%以上的土壤甲烷减排，揭幕。好氧核心是由表层土壤中的好氧甲烷营养细菌进行的，在稳定细菌群落方面发挥了重要作用。厌氧核心是缺氧土壤中的反硝化甲烷生物，包括来自NC10门的反硝化甲烷营养细菌和来自ANME-2d进化枝的反硝化甲烷营养古细菌。它们在陆地土壤中普遍存在，并可能导致约50％的甲烷去除量。畜牧业和水稻种植等人类活动进一步促进了这些反硝化甲烷生物的贡献率。这项工作阐明了大陆环境中不同甲烷营养生物的减排贡献，这将有助于减少土壤甲烷排放量估算中的不确定性。
