Team Play: Determining Syntrophic Interactions in Hydrocarbon Biodegradation Processes

自然界中的微生物以混合群落的形式存在，它们的集体新陈代谢极大地促进了生物地球化学和/或营养循环--这些现象可能会对全球健康产生深远影响，包括我们的气候、水和土地资源。在缺氧环境中，由细菌和古生菌组成的混合微生物群落能够通过一种称为合成营养的代谢过程将有机物生物转化为甲烷。同化被定义为热力学上相互依赖(互惠)的代谢，其中混合厌氧群落中的不同物种必须合作进行给定的代谢反应，而不是每个生物体单独分解。这种“团队合作”新陈代谢在热力学平衡附近运行，但在湿地、动物内脏、垃圾填埋场、稻田和废水处理系统等缺氧生态系统中，有机物质自然循环为CH4和CO2有很大贡献，在与碳氢化合物相关的缺氧生态系统中，如天然气和天然气渗漏、深层地下能源库和被浅层碳氢化合物污染的地下水系统，这是一个普遍的过程。然而，包括碳氢化合物在内的大多数有机化合物共养代谢的生态学原理仍有待充分探索。我的研究计划的总体、长期目标是确定支配与产甲烷烃生物降解过程相关的合养群落的相互作用。这项拟议工作的两个主要短期目标将解决这一研究领域的知识空白问题，即(1)确定混合联合体中知之甚少的合养成员的相互作用和潜在作用，包括在我们的产甲烷培养物和其他环境中已确定的未经培养的分类群(如‘Atri细菌’)和其他社区成员的相互作用和潜在作用，以及(2)实验性评估降解产甲烷碳氢化合物的社区成员(例如通过间接或直接的物种间电子转移、中间体或营养物质相互依赖)相互建立互利伙伴关系的机制。拟议的研究计划将提供对微生物群落成员如何集体相互作用以生物转化有机物的见解，从而有助于更广泛地了解生物地球化学循环。将重点放在正在进行这种“团队合作”的碳氢化合物降解系统上，将有助于我们更好地理解如何最好地应用生物解决方案来补救加拿大和其他地方的碳氢化合物污染环境。

Microorganisms in the natural world exist as mixed communities whose collective metabolism substantially contributes to biogeochemical and/or nutrient cycling - phenomena that can have profound impacts on global health including our climate, water, and land resources. In anoxic environments, mixed microbial communities comprised of Bacteria and Archaea are able to biotransform organic matter to methane through a metabolic process known as syntrophy. Syntrophy is defined as a thermodynamically interdependent (mutualistic) metabolism wherein different species within mixed anaerobic communities must cooperate to carry out a given metabolic reaction that cannot be catabolized by each organism alone. Such `team play' metabolism operates near the thermodynamic equilibrium, yet contributes substantially to the natural cycling of organic matter to CH4 and CO2 in anoxic ecosystems such as wetlands, animal guts, landfills, rice paddies, and wastewater treatment systems, and is a prevalent process in anoxic hydrocarbon-associated ecosystems such as natural oil and gas seeps, deep subsurface energy reservoirs, and shallow hydrocarbon-contaminated groundwater systems. However, the ecological principles underlying the syntrophic metabolism of most organic compounds, including hydrocarbons, remain to be fully explored. The over-arching, long-term objective of my research program is to determine the interactions that govern syntrophic communities associated with methanogenic hydrocarbon biodegradation processes. The two major short-term objectives for the proposed work that will address gaps in knowledge in this field of study are to (1) identify the interactions and potential roles of poorly understood syntrophic members in mixed consortia, including those of uncultivated taxa (such as `Atribacteria') and other community members that have been identified in our hydrocarbon-metabolizing methanogenic cultures and in other environments, and (2) to experimentally assess mechanisms used by methanogenic hydrocarbon-degrading community members (such as via indirect or direct interspecies electron transfer, mediators, or nutrient interdependencies) to form mutually beneficial partnerships with each other. The proposed research program will offer insights into how microbial community members collectively interact to biotransform organic matter thus contributing to a broader understanding of biogeochemical cycling. The focus on hydrocarbon-degrading systems undergoing such `team play' will help to improve our understanding of how best to apply biological solutions to remediate hydrocarbon-contaminated environments in Canada and elsewhere.