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，由细菌和微生物群组成的混合微生物群落能够通过称为合成营养的代谢过程将有机物质生物转化为甲烷。互养被定义为一种生物学上相互依赖的（互利的）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，该代谢反应不能单独被每种生物体分解代谢。这种“团队合作”的新陈代谢在热力学平衡附近进行，但对湿地、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到甲烷和二氧化碳的自然循环有很大贡献，而且是天然油气渗漏、深层地下能源储藏、和浅层烃污染地下水系统。然而，包括碳氢化合物在内的大多数有机化合物的互养代谢的生态学原理仍有待充分探索。我的研究项目的长期目标是确定与产甲烷烃生物降解过程相关的互养群落的相互作用。两个主要的短期目标，为拟议的工作，将解决知识的差距，在这一领域的研究是（1）确定相互作用和潜在的作用，了解不多的互养成员在混合财团，包括那些未培养的类群（如“Atribacteria”）和其他社区成员，已确定在我们的烃代谢产甲烷的文化和其他环境中，和（2）实验评估产甲烷烃降解群落成员（如通过间接或直接的物种间电子转移，介质，或营养相互依赖性），以形成互利的伙伴关系，彼此使用的机制。拟议的研究计划将提供深入了解微生物群落成员如何共同相互作用，以生物转化有机物质，从而有助于更广泛地了解生物地球化学循环。对正在进行这种“团队合作”的碳氢化合物降解系统的关注将有助于我们更好地了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.