Defining the molecular basis of microbial syntrophy using synthetic communities

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This research project addresses the study of a group of poorly understood microorganisms called syntrophic bacteria and their methanogenic archaea partners that play essential roles in the anaerobic recycling of all naturally occurring biomass. They function as members of microbial communities that consume decaying plant and animal material and convert it back into the starting materials needed for photosynthesis by plants and algae. The syntrophic bacteria first break down and recycle small organic molecules such as fats, amino acids and small aromatic compounds. The resulting waste products (vinegar, water and hydrogen gas) are then used by a second group of microbes called methanogens to generate more water plus carbon dioxide and methane. Methane can be harvested and used as a renewable energy supply. Through this cooperation, both microbes obtain energy to survive and grow in environments where neither could alone. A combination of molecular and biochemical tools is used to study the previously undescribed metabolism in each microbe and to understand how they cooperate with one another to optimally recycle waste materials in nature. The enzymes used in substrate conversion will be identified and characterized; and how cells accomplish the exchange of metabolites will be examined. The new knowledge will assist in modeling and predicting how carbon is recycled in different environments, as well as how these processes affect the normal maintenance of the earth's biosphere. Furthermore, it will improve our ability to recycle unwanted waste materials into renewable energy supplies. In outreach activities, web-based learning materials will be generated and used to enhance undergraduate microbiology instruction at both institutions. In addition, the PIs will perform outreach activities in several under-developed countries to facilitate the development of locally sustainable applications for waste treatment and energy production.Syntrophic metabolism is essential in nearly all anaerobic ecosystems, yet very little is understood about the molecular, biochemical, or physiological events that drive the associated ecological transformations. Here, microbial communities composed of distinct species of bacteria and archaea operate in metabolic balance to drive global carbon cycling and ecosystem functioning. The PIs hypothesize that specialized biochemical and adaptive systems are used by the syntrophic partners to accomplish their community-driven metabolism. To examine this, the model Syntrophomonas wolfei/Methanosprillum hungatei co-culture system will be employed to elucidate basic principles governing formation and maintenance of the syntrophic partnership. A combination of high-throughput technologies, including genome-wide proteomic profiling and genetic two hybrid screens, will be employed to identify the metabolic and regulatory networks involved in fatty acid catabolism. This will be followed by the biochemical characterization of key proteins needed for carbon oxidation and electron flow down to the formation of H2 and CO2 which is a thermodynamically difficult process. The molecular events required to establish and maintain a related but distinct co-culture partnership, that between S. wolfei and Methanobrevibacter ruminantium will also be examined. The resulting information will provide a foundation to model and predict related processes by other multispecies microbial communities. The new knowledge will be used to develop innovative solutions for waste treatment and energy production and to engineer bio-methanation and microbial fuel systems to provide locally sustainable applications for wastewater treatment. This award is jointly funded by the Cellular Dynamics and Function and the Systems and Synthetic Biology Programs in the Division of Molecular and Cellular Biosciences.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.