Understanding syntrophic hydrocarbon metabolism under methanogenic conditions

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Hydrocarbon spills into subsurface environments such as groundwater aquifers frequently lead to the development of methanogenic conditions. Many studies have shown that hydrocarbons can be biodegraded to methane by microbes, suggesting that we may be able to rely on such microbial activity for contaminated site clean up. To do so, we must have a better understanding of how this metabolism operates in order to determine the advantages and limitations of relying on methanogenic consortia for remediation. Syntrophy, meaning ‘feeding together’, is a mode of microbial metabolism wherein different species must cooperate (for thermodynamic reasons) to carry out metabolic processes. Syntrophic microbial processes play key roles in large-scale beneficial industrial processes such as waste water treatment and make significant contributions to carbon cycling in anaerobic ecosystems. As such, syntrophy has mainly been studied using microbes that metabolize relatively simple carbon sources (such as fatty acids). As with fatty acids, methanogenic hydrocarbon metabolism must occur via syntrophic processes wherein cooperation among microbial species is needed to break down a given hydrocarbon to carbon dioxide and methane. However, little is known about the ecological principles of syntrophy in hydrocarbon-containing methanogenic ecosystems. Thus, the long-term objective of this research program is to elucidate the fundamental scientific principles underlying syntrophic hydrocarbon metabolism under methanogenic conditions that will be accomplished via two major short-term objectives. Objective 1 will be to improve upon and/or develop new strategies for cultivating syntrophic hydrocarbon-degrading methanogenic consortia in order to decrease lag times and improve rates of metabolism to enable more efficient study of syntrophic hydrocarbon metabolism. This objective will use a cultivation approach to test the use of various medium additives, solid supports, and growth conditions to improve rates of metabolism. Objective 2 will be to identify and quantify the key syntrophy genes and hydrocarbon-degrading genes that are expressed during methanogenic hydrocarbon metabolism using molecular biology approaches. This information is currently unknown. The proposed research will address major gaps in the fields of syntrophy and methanogenic hydrocarbon metabolism, leading to fundamental scientific discoveries and potential applications for contaminated site remediation.  The outcome of the research will be of great benefit to Canada by helping to ensure clean environments (such as groundwater resources). Through the proposed program, many highly qualified personnel will be trained in diverse technical skills (ranging from analytical chemistry to genomics) and soft skills (leadership, communication) that will position them well for jobs in academia, industry, or government.