SusChEM: Collaborative Research: Biogenic Methanogenesis and Biodegradation of Organic Matter in Coals

更广泛的意义。天然气主要由甲烷组成，约占美国总能源的四分之一，因此是美国经济的主要基石。2010年，煤层气（CBM）约占美国国内天然气总产量的9%，美国能源情报署（USEIA）估计，到2035年及以后几年，煤层气将继续成为美国能源组合的重要组成部分。通过最近对深层含煤沉积盆地的工作和观察，微生物控制着甲烷的产生已经变得很明显，然而令人惊讶的是，人们对控制这些微生物的原因知之甚少。由于开发替代能源的持续需求，以及与从这些来源（特别是水力压裂）中回收天然气相关的宣传，公众、监管机构和工业界对从非常规资源中回收天然气的兴趣越来越大。预计到2035年，煤层气产量将保持不变，平均每年1.8万亿立方英尺（CF）。根据目前天然气的价格为4.57美元/百万英热单位和2013年美国天然气协会（USEIA）的平均热量含量（102.5万英热单位/103立方英尺），煤层气的生产价值约为84.3亿美元/年。该项目的研究人员建议确定产生CBM的群落中的组成生物，重要的是，是什么影响了它们导致甲烷产生的代谢过程。有了这些知识，就有可能增加煤层气的生物生产，并提供一种更加稳定和有利可图的燃料资源。基于上述年产量，即使将目前的生物煤层气产量提高0.1%，也将产生843万美元/年的经济回报。这项研究得到了NSF可持续化学、工程和材料（SusChEM）计划的支持。技术描述。本研究的重点是表征地下cbm相关微生物代谢的基因型和调控网络。它试图建立在我们最初的生物地球化学研究的基础上，通过阐明微生物群落结构和控制实验室培养下生物反应器富集的功能调节，研究煤提取物与微生物培养过程中碳氢化合物组成的变化。具体来说，我们将确定低浓度的终端电子受体对微生物群落动态的影响，这些动态与有机物降解增加和甲烷产生速率的改变有关。我们将描述每个系统的关键组分的基因型，并确定它们的相对丰度如何随时间和终端电子受体浓度的实验操作而变化。我们还将绘制其基因在实验条件和时间下的转录图谱，以确定其对煤中复杂有机碳代谢的潜在影响。这些数据与每个生物反应器实验的物理化学参数化相结合，将产生微生物组合的分区代谢模型。这个模型将是同类模型中的第一个，为更复杂系统的新陈代谢建模奠定基础。

Broader significance.Natural gas, composed primarily of methane, provides approximately a quarter of the total energy in the US and is therefore a major cornerstone of the US economy. Coalbed methane (CBM) provided about 9% of the total domestic natural gas production in 2010 and the U.S. Energy Information Administration (USEIA) estimates that CBM will continue to be an important part of the US energy portfolio through 2035 and in subsequent years. Through recent work and observation of deep coal-bearing sedimentary basins, it has become obvious that microbes are controlling the generation of this methane, and yet surprisingly little is known about what controls these microbes. There is growing public, regulatory, and industrial interest in recovery of natural gas from unconventional sources because of the continued need to develop alternative energy sources and the publicity associated with gas recovery from such sources, especially hydraulic fracturing (fracking). CBM production is estimated to remain constant through 2035, averaging 1.8 trillion cubic feet (CF) per annum. Based on a current price of $4.57/MMBtu and the USEIA 2013 average heat content for natural gas (1.025 MMBtu/103 CF), CBM production has a value of approximately $8.43 billion/year. The investigators on this project propose to identify the component organisms in the communities that generate CBM, and importantly, what influences their metabolic processes leading to methane production. Armed with this knowledge it may be possible to increase the biogenic production of CBM, and provide a significantly more stable and profitable fuel resource. Enhancing current biogenic CBM production by even a modest 0.1% would, based on the above annual production value, would have an economic return of $8.43 million/year. This research is supported via the NSF Sustainable Chemistry, Engineering, and Materials (SusChEM) initiative.Technical description.The proposed research focuses on characterizing the genotypes and regulatory networks that mediate CBM-associated microbial metabolism in the subsurface. It seeks to build on our initial biogeochemical investigation of changes in hydrocarbon composition that accompany microbial incubations with coal extracts by elucidating the microbial community structure and functional regulation in bioreactor enrichments under controlled laboratory incubations. Specifically, we will determine the influence of low concentrations of terminal electron acceptors on microbial community dynamics associated with increased organic matter degradation and altered rates of methane production. We will describe the genotypes of key components of each system, and determine how their relative abundance shifts over time and across experimental manipulations of terminal electron acceptor concentration. We will also map the transcription of their genes in response to experimental conditions and time, to determine the potential influence on the metabolism of the complex organic carbon in coals. These data, in concert with the physic-chemical parameterization of each bioreactor experiment will be combined to generate a compartmentalized metabolic model of the microbial assemblage. This model will be a first of its kind, laying the groundwork for modeling the metabolism of more complex systems.