SBIR Phase I: High-Temperature Fermentation for Volatile Organic Chemical Production

About This Grant

The broader/commercial impact of this Small Business Innovation Research (SBIR) Phase I project ultimately includes improving domestic chemical supply chains by enhancing the capability of a hyperthermophile organism to produce volatile organic compounds (VOCs), namely ethanol and acetone. The United States consumes approximately 14.2 billion gallons of ethanol and 0.5 billion gallons of acetone per year in widespread use as a fuel additive and industrial solvent, respectively. Currently, most American bioethanol is produced from corn-derived sugars using a relatively low-temperature, yeast-dependent bioprocess whereas most acetone is produced from fossil fuels using the cumene process. High-temperature bioprocess exhibits several distinct advantages over low-temperature bioprocess, including intrinsic resistance to contamination by other microbes and simplified product separation through continuous VOC distillation. Despite the promising attributes of high-temperature bioprocess as a technology, implementation has not been feasible due to insufficient product yields. This project aims to use novel synthetic biology methods to improve VOC production of a hyperthermophile. Success and implementation of this project has the potential to improve American fuel and chemical feedstock independence while increasing demand for domestic agricultural markets. The proposed project seeks to engineer a strain of high-temperature microbe to produce volatile organic chemicals, primarily ethanol and acetone, to investigate whether this type of microbe could feasibly be used for large-scale biomanufacturing. While microbial ethanol production is common, it faces a variety of challenges related to low reaction rate, high energy use, poor compatibility with lower-cost feedstocks, sensitivity to environmental contaminants, complicated product separation, and inflexibility to products beyond ethanol. The same is true of microbial acetone and isopropanol production, which have not seen industrial use in nearly a century. A high-temperature system can address these challenges through faster reaction rates, less heat wastage from process cooling, passive thermal degradation of feedstocks and environmental contaminants, continuous product distillation, and improved metabolic flexibility. This project will use metabolic engineering techniques to re-route carbon and energy from the production of organic acids, which are inhibitory to growth, low-value, and challenging to isolate, and towards volatile organic chemicals like ethanol, acetone, and, if time allows, isopropanol using plant fibers as a feedstock. This is done by upregulation, downregulation, and knockout of native enzymes and/or by heterologously expressing enzymes from other high-temperature microbes. 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.