Dissertation Research: Microbial Community Structure and Ecosystem Function: Linking Methanogen Community Composition to Methane Production Rates in Wetland Soils

这项研究将探索密歇根州北部泥炭地存在的微生物群落与甲烷生产之间的关系。泥炭地产生大量的甲烷，这是一种强大的温室气体，每单位重量捕获的热量是二氧化碳的25倍，造成了近五分之一的人类造成的全球气候变化。甲烷是由产甲烷菌（古细菌领域的一组微生物）通过两种途径产生的。这些途径是由不同的产甲烷菌群完成的，因此了解现有的产甲烷菌与甲烷产量之间的关系对于理解泥炭地对未来全球气候变化的贡献至关重要。由于绝大多数产甲烷菌仍然是不可培养的，因此有必要使用一种与培养无关的、基于基因的方法来鉴定环境中存在的产甲烷菌。在这些研究中，所有已知产甲烷菌中参与产甲烷的基因mcrA将被用作分子标记。将对泥炭样品中的mcrA DNA和mRNA进行测序，以鉴定存在的产甲烷菌，并量化其生物多样性。高通量测序的使用将允许前所未有的跨越空间和时间的复制，并且由此产生的甲烷菌数据将与泥炭样品中测量的甲烷生成率以及温度、pH值和水化学等环境因素相关联。这个博士论文的改进项目将有助于了解北方泥炭地的甲烷产量，这是温室气体的一个重要来源。除了加强对博士生的培训外，该项目还将为一些本科生提供研究经验，包括那些来自科学界代表性不足的群体的本科生。

This study will explore the relationship between the community of microbes present and the production of methane in peatlands in northern Michigan. Peatlands produce significant amounts of methane, a powerful greenhouse gas that traps 25 times more heat than carbon dioxide per unit weight, and drives almost a fifth of human-caused global climate change. Methane is produced by methanogens, a group of microorganisms in the domain Archaea, via two pathways. These pathways are carried out by distinct groups of methanogens, so understanding the relationship between the methanogens present and methane production rates is essential to understanding the contribution of peatlands to future global climate change. Because the overwhelming majority of methanogens remain unculturable, it is necessary to use a culture-independent, gene-based approach to identify the methanogens present in the environment. For these investigations, mcrA, a gene involved in methanogenesis in all known methanogens, will be used as a molecular marker. mcrA DNA and mRNA from peat samples will be sequenced to identify the methanogens present, and to quantify their biodiversity. The use of high-throughput sequencing will allow an unprecedented level of replication across space and through time, and the resulting methanogen data will be correlated to measured rates of methanogenesis in the peat samples, along with environmental factors such as temperature, pH, and water chemistry. This doctoral dissertation improvement project will contribute to the understanding of methane production rates in boreal peatlands, a highly significant source of this greenhouse gas. In addition to enhancing the training of a doctoral student, this project will provide research experience for several undergraduates including those from groups underrepresented in science.