SusChEM: Collaborative Research: Efficient biological activation and conversion of short-chain hydrocarbons

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Advances in the recovery of oil and gas reserves, through the use of fracking and horizontal well drilling, for example, have dramatically increased the amount of natural gas that can be economically harvested in the US. These reserves also contain compounds, know as natural gas liquids (NGLs), that are expensive to convert to useful products using current refinery technology. Fortunately, many microorganisms are capable of consuming NGLs for biomass and energy production using pathways that are much more efficient and less expensive. The biological mechanisms of these conversions will be studied in order to design organisms that exhibit even greater yield of product. By eliminating the generation of waste products and enhancing the effectiveness of these microbes, the resulting technology will be more widely deployed at fracking sites, increasing the energy security of the US while decreasing the negative environmental impact of natural gas extraction. This project will also provide STEM research opportunities to traditionally underrepresented groups, including to high school students through outreach to high schools in Houston, through the Science Academy of South Texas, and through the McNair program at Penn State.By cloning and repurposing poorly understood alkane-metabolizing enzymes, this project aims to develop metabolically engineered microorganisms capable of converting short-chain alkanes to target products such as butanol. Harnessing alkylsuccinate synthases for such biocatalytic applications requires functionally expressing their partner "activase" enzymes, that require iron-sulfur cluster incorporation, in a microbial host amenable to metabolic engineering. Screens for functional expression of known or putative enzyme pairs and for activation by non-cognate activases will be executed. Enzyme directed evolution strategies to achieve alkylsuccinate synthase activation will also be employed. Functional, heterologous partners will be thoroughly characterized, providing new insights into activase-alkylsuccinate synthase interaction, and new opportunities for biotechnological applications of these and related enzymes. The overall research plan combines protein and metabolic engineering to establish a novel engineering platform for biocatalytic processes with enhanced carbon and energy efficiencies. If successful, this project could transform the commercial processing of NGL away from large, capital- and energy-intensive refinery processing to smaller-scale processes with high mass and energy efficiency. This would in turn eliminate a major source of waste involved in natural gas processing.