BP: Improving butanol fermentation to enter the advanced biofuel market. mBio 2012

ABSTRACT 1-Butanol is a large-volume, intermediate chemical with favorable physical and chemical properties for blending with or directly substituting for gasoline. The per-volume value of butanol, as a chemical, is sufficient for investing into the recom-mercialization of the classical acetone-butanol-ethanol (ABE) (E. M. Green, Curr. Opin. Biotechnol. 22:337–343, 2011) fermenta-tion process. Furthermore, with modest improvements in three areas of the ABE process, operating costs can be sufficiently de-creased to make butanol an economically viable advanced biofuel. The three areas of greatest interest are (i) maximizing yields of butanol on any particular substrate, (ii) expanding substrate utilization capabilities of the host microorganism, and (iii) reduc-ing the energy consumption of the overall production process, in particular the separation and purification operations. In their study in the September/October 2012 issue ofmBio, Jang et al. [mBio 3(5):e00314-12, 2012] describe a comprehensive study on driving glucose metabolism in Clostridium acetobutylicum to the production of butanol. Moreover, they execute a metabolic engineering strategy to achieve the highest yet reported yields of butanol on glucose. In efforts to develop renewable alternatives to petroleum-basedchemicals and fuels, there is rejuvenated interest in clostridial acetone-butanol-ethanol (ABE) fermentation. ABE fermentation was first commercialized in the 1910s in the United Kingdom for the production of acetone, which was used as a solvent in the production of cordite, a smokeless ammunition propellant (1)