Synthetic Biology Approaches to Produce C3-C6 Alcohols from Microorganisms

Biofuels synthesized from renewable resources are of increasing interest because of global energy and environmental problems. Compared to the traditional biofuel, ethanol, higher alcohols such as isobutanol and 1-butanol offer advantages such as higher energy density, lower hygroscopicity, lower vapor pressure, and compatibility with existing transportation infrastructure. Some Clostridia species are known to naturally produce isopropanol and 1-butanol. However, these fuels are not synthesized economically using native organisms. Additionally, other C3-C6 alcohols are not produced in large quantities by natural microorganisms. Synthetic biology offers an alternative approach in which synthetic pathways are engineered into user-friendly hosts for the production of these fuel molecules. These hosts could be readily manipulated to improve the production efficiency. This review summarizes recent progress in the engineering of microorganisms to produce C3-C6 alcohols.