| Project Detail |
A robust and sustainable bioeconomy can only be realized through the industrial-scale, carbon-neutral synthesis of fuels, chemicals, and materials. Biofuels, along with a growing number of other sustainable products, are made almost exclusively via fermentation, the age-old technology used to produce foods such as wine, beer, and cheese. Current commercial methods to produce ethanol biofuel from sugar or starches waste more than 30% of the carbon in the feedstock as carbon dioxide (CO2) in the fermentation step alone. This waste limits product yields and squanders valuable feedstock carbon as greenhouse gas CO2. Preventing the loss of carbon as CO2 during bioconversion, or directly incorporating external CO2 as a feedstock into bioconversions, would revolutionize bioprocessing by increasing the product yield per unit of carbon input by more than 50%.
Project Innovation + Advantages:
The Massachusetts Institute of Technology (MIT) has demonstrated a two-stage system where acetate is produced from CO2 and H2 via acetogenic fermentation in the first stage and then fed to the yeast reactor for converting acetate to lipids or alkanes. MIT proposes to reduce or eliminate CO2 generation during lipid production by (1) engineering an oleaginous yeast with the enzymes necessary to generate reducing equivalents from hydrogen, formic acid, or methanol, and (2) installing a carbon-conserving non-oxidative glycolysis. The system’s commercial competitiveness is currently limited by the rate of CO2 fixation in the first stage. MIT recently showed that synergistic substrate co-feeding drastically enhances CO2 fixation rates and will explore additional co-substrate pairs to maximize acetate productivity.
Potential Impact:
The application of biology to sustainable uses of waste carbon resources for the generation of energy, intermediates, and final products---i.e., supplanting the “bioeconomy”—provides economic, environmental, social, and national security benefits and offers a promising means of carbon management. |
