Physiological and Molecular Diversity of Atmospheric CH4 Oxidizers in Soil

土壤中大气 CH4 氧化剂的生理和分子多样性

• 批准号: 9708092
• 负责人: Paul Steudler
• 金额: $ 60万
• 依托单位: Marine Biological Laboratory
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1997
• 资助国家: 美国
• 起止时间: 1997-08-15 至 2001-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9708092&HistoricalAwards=false
• 关键词: Physiological; Molecular; Diversity; Atmospheric; CH4

ABSTRACT STEUDLER (97-08092) Atmospheric CH4 contributes substantially to the greenhouse effect and has increased dramatically in the past century because of human activity associated with agriculture and industrial expansion. Consumption of atmospheric CH4 in well-drained soils is an important regulator of atmospheric CH4 concentration. The significance of the soil sink lies not in its magnitude relative to the global CH4 budget, but rather in its potential to mediate long-term, anthropogenic effects on atmospheric CH4 through its response to disturbance. Soil CH4 consumption is very sensitive to land-use changes, such as agriculture and forest clearcutting, and also may be sensitive to climate change factors, such as drought or soil warming. Because the amount of atmospheric CH4 consumed annually in soil is comparable to the annual increase in atmospheric CH4 over the past decade, the cumulative effects of disturbance on the soil CH4 sink over time could contribute significantly to CH4 accumulation in the atmosphere. However, the biology of this process is poorly understood because researchers have yet to determine what type(s) of soil bacteria actually oxidize atmospheric CH4 in situ. This project will investigate the physiology and molecular ecology of atmospheric CH4 oxidizers in four temperate and taiga forest ecosystems where disturbance effects on soil CH4 consumption have been well characterized. The study focuses on the following questions: (1) What are the physiological characteristics of the atmospheric CH4 oxidizers in a given soil?, (2) What types of organisms oxidize atmospheric CH4 in a given soil: Methanotrophs or Nitrifiers? and (3) How does the ecosystem type and disturbance regime affect which group of organisms is active in a given soil? A number of laboratory and field process-level measurements including CH4 starvation and enrichment experiments, kinetic studies and differential inhibitors will be used to access the microbial community response across the suit e of study sites. Phylotype distribution and functional gene studies will be used to characterize the methanotropic and/or nitrifier communities within and across the study sites. This research will provide an estimate of the biodiversity among soil atmospheric CH4 oxidizers, examine how this diversity is distributed in nature and assess how important this diversity is in controlling the ecosystem-level response of soil CH4 consumption to disturbance and climate change. The strategy is scientifically unique in that it will bring the power of modern molecular biology to bear on ecosystem-level process ecology. It will allow the qualitative quantitative examination of the relationship between in situ process dynamics and the molecular ecology of the microbial community, thus improving understanding of the biological controls over soil CH4 consumption, which remains the most enigmatic dimension of the soil CH4 sink. Methane oxidation is an ideal model for initiating this type of approach because it is a highly specialized physiology, and because substrate supply can be controlled precisely in laboratory incubations. Future investigations on other biogeochemical processes will benefit from experience gained during this research.

摘要 STEUDLER（97-08092） 大气中的甲烷是温室效应的重要组成部分，在过去的世纪，由于人类活动与农业和工业扩张的关系，甲烷的含量急剧增加。排水良好的土壤对大气CH 4的消耗是大气CH 4浓度的重要调节因子。土壤汇的重要性不在于其相对于全球CH 4收支的大小，而在于其通过对扰动的响应来调节长期的、人为的对大气CH 4的影响的潜力。土壤CH 4消耗对土地利用变化非常敏感，如农业和森林皆伐，也可能对气候变化因素敏感，如干旱或土壤变暖。由于土壤中每年消耗的大气CH 4量与过去十年大气CH 4的年增长量相当，因此随着时间的推移，扰动对土壤CH 4汇的累积效应可能会显著促进CH 4在大气中的累积。然而，人们对这一过程的生物学知之甚少，因为研究人员尚未确定哪种类型的土壤细菌实际上在原位氧化大气中的CH 4。 本项目将调查四个温带和针叶林生态系统中大气CH 4氧化剂的生理学和分子生态学，在这些生态系统中，干扰对土壤CH 4消耗的影响已得到很好的表征。本研究主要探讨以下几个问题：（1）土壤中大气CH 4氧化剂的生理特性是什么？(2)什么类型的生物氧化大气中的甲烷在一个给定的土壤：甲烷氧化菌或硝化？（3）生态系统类型和干扰状况如何影响特定土壤中活跃的生物类群？ 许多实验室和现场工艺水平的测量，包括CH 4饥饿和富集实验，动力学研究和差异抑制剂将用于访问整个研究地点的微生物群落响应。将使用系统型分布和功能基因研究来表征研究中心内和研究中心间的嗜甲烷菌和/或硝化菌群落。 这项研究将提供土壤大气CH 4氧化剂的生物多样性的估计，研究这种多样性是如何分布在自然界中，并评估这种多样性是如何重要的是在控制生态系统层面的响应土壤CH 4消费的干扰和气候变化。这一战略在科学上是独一无二的，因为它将把现代分子生物学的力量带到生态系统层次的过程生态学上。它将允许对原位过程动态与微生物群落分子生态学之间的关系进行定性定量检查，从而提高对土壤CH 4消耗的生物控制的理解，这仍然是土壤CH 4汇中最神秘的维度。甲烷氧化是启动这种方法的理想模型，因为它是一种高度专业化的生理学，并且因为底物供应可以在实验室孵育中精确控制。今后对其他地球化学过程的研究将受益于这项研究中获得的经验。