Biomass to Butanol via Engineered Yeast

by Emil Morhardt

Butanol is a four-carbon alcohol, next in size after 1-C methanol (wood alcohol), 2-C ethanol (drinking alcohol), and 3-C propanol (rubbing alcohol), so it shouldn’t come as any surprise that yeast ought to be able to synthesize it out of sugar. And it burns like the other alcohols mentioned, so it is potentially a usable liquid fuel that could be mixed with gasoline (like ethanol, to increase it’s non-fossil-fuel content), processed into other types of fuel, or used as commercial feedstock to make bio-based commercial plastics such as the PET (polyethylene terephthalate) used to make beverage bottles. Gevo, Inc., a company based in Englewood, Colorado but with it’s only [troubled] production facility in Luverne, Minnesota, seems to be gradually overcoming myriad difficulties in commercializing biomass-based isobutanol, and is beginning to license its proprietary genetically-modified yeast, which produce more isobutanol than conventional ethanol-producing commercial varieties. Gevo hopes that these yeast will feel right at home in existing ethanol-production facilities (such as the Luverne plant, where they didn’t do so well initially), and that all Gevo will have to do to get isobutanol out is to bolt on a module that separates the isobutanol from the water in which the yeast are living. Continue reading