Tuesday, May 1, 2012: 8:30 AM
Rhythms Ballroom, 2nd fl (Sheraton New Orleans)
The search for an alternative to petroleum has renewed interest in the biological production of 1-butanol and acetone using solventogenic Clostridia. In situ removal of the inhibitory product 1-butanol during fermentation has been shown to increase solvent production and yield. Extractive fermentation utilizes a non-toxic, water-immiscible extractant to selectively remove inhibitory compounds from the fermentation broth. Currently no extractant has been identified as non-toxic and capable of efficiently extracting both 1-butanol and acetone from a fermentation broth. The goal of this work is to improve acetone and 1-butanol productivities and yields by extractive fermentation of C. acetobutylicum. Extractant distribution coefficients (KD) for acetone and 1-butanol were measured in a simulated fermentation medium by HPLC and GC. Extractant toxicity to C. acetobutylicum was measured by both growth inhibition and cell viability up to volume ratios of 1:1 (extractant:cell culture). Non-toxic extractants discovered in this work efficiently removed both acetone (KD= 1.0-1.1) and 1-butanol (KD= 2.4-2.6) from an aqueous environment. Extractive fermentations carried out in a 1:1 volume ratio of extractant to media resulted in 18.3 g/L and 4.3 g/L of 1-butanol and acetone, respectively, in the extractant phase. These solvents were then catalytically condensed to form primarily C7 to C16 mono-oxygenated hydrocarbons, to serve as precursors for gasoline, jet, and diesel fuels. This work shows a new promising route to improve the production and recovery of acetone and 1-butanol during fermentation to produce fungible fuels.