Genetic manipulation of non-solvent-producing microbial species for effective butanol production

Butanol is widely used as an important bulk chemical and is a potential biofuel. The depletion of fossil fuels and advances in synthetic biotechnology have led to renewed interest in the biological production of butanol. Solventogenic Clostridium was commonly used to produce butanol through traditional acetone-butanol-ethanol (ABE) fermentation. However, its relatively slow growth rate, low butanol tolerance, and poor production efficiency have hindered the further application of this procedure. Recently, other promising industrial hosts, including Escherichia coli, Saccharomyces cerevisiae, and Clostridium tyrobutyricum, have been studied for potential use in the production of butanol. This review comprehensively summarizes the advantages and challenges of different non-solvent strains for butanol production to identify better the ideal non-solvent hosts for butanol production. Strategies to further increase butanol production are also proposed.