Physiological and Molecular Diversity of Atmospheric Methane (CH4) Oxidizers in Soil

大气甲烷在很大程度上造成了温室效应，在过去的一个世纪里，由于农业和工业的发展，甲烷的数量急剧增加。土壤中甲烷的细菌消耗是大气甲烷浓度的重要调节因素。土壤汇的意义在于它有可能通过对农业、森林砍伐、干旱和土壤变暖等干扰的反应来调节对大气甲烷的长期人为影响。由于土壤中每年消耗的大气甲烷量与大气甲烷的年增加量相当，随着时间的推移，干扰对土壤甲烷汇的累积影响可能会对大气中的甲烷积累做出重大贡献。然而，人们对土壤汇的生物学知之甚少，因为研究人员尚未识别和全面描述在现场实际氧化大气甲烷的土壤细菌。在这个项目中，Steudler博士和他的同事将在五个温带和泰加森林生态系统中研究大气甲烷氧化剂的生理学和分子生态学，在这些生态系统中，对大气甲烷消耗的干扰效应得到了很好的表征。他们的目标是评估甲烷氧化生物之间的跨地点多样性在控制土壤甲烷消耗对包括氮肥、干旱和土壤变暖在内的干扰的响应中所起的作用。这项研究将提供对地理上遥远和生态上不同的森林生态系统中土壤大气甲烷氧化剂微生物多样性的估计，审查这种多样性在自然界中相对于生物地球化学过程动力学和生态梯度的分布情况，并评估这种多样性在控制土壤甲烷消费对干扰和气候变化的生态系统一级反应方面的重要性。

Atmospheric methane contributes substantially to the greenhouse effect and has increased dramatically in the past century because of expanding agriculture and industry. Bacterial consumption of methane in soils is an important regulator of atmospheric methane concentration. The significance of the soil sink lies in its potential to mediate long-term, anthropogenic effects on atmospheric methane through its response to disturbances such as agriculture, forest clearcutting, drought, and soil warming. Because the amount of atmospheric methane consumed annually in soils is comparable to the annual increase in atmospheric methane, the cumulative effects of disturbance on the soil methane sink over time could contribute significantly to methane accumulation in the atmosphere. However, the biology of the soil sink is poorly understood because researchers have yet to identify and fully describe the soil bacteria that actually oxidize atmospheric methane in situ. In this project, Dr. Steudler and colleagues will investigate the physiology and molecular ecology of atmospheric methane oxidizers in five temperate and taiga forest ecosystems where disturbance effects on atmospheric methane consumption are well characterized. Their goal is to assess the role of cross-site diversity among the methane oxidizing organisms in controlling the soil methane consumption response to disturbances, including N fertilization, drought and soil warming. This research will provide an estimate of microbial diversity among soil atmospheric methane oxidizers across geographically distant and ecologically distinct forest ecosystems, examine how this diversity is distributed in nature relative to biogeochemical process dynamics and ecological gradients, and assess how important this diversity is in controlling the ecosystem-level response of soil methane consumption to disturbance and climate change.