ARS | Publication request: Bioproduction of butanol in bioreactors: new insights from simultaneous in situ butanol recovery to eliminate product toxicity

Submitted to: Biotechnology and Bioengineering
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 22, 2011
Publication Date: August 1, 2011
Citation: Mariano, A.P., Qureshi, N., Filho, R.M., Ezeji, T.C. 2011. Bioproduction of butanol in bioreactors: new insights from simultaneous in situ butanol recovery to eliminate product toxicity. Biotechnology and Bioengineering. 108(8):1757-1765.

Interpretive Summary: Butanol is a superior liquid biofuel than ethanol and packs 30% more energy on a gallon basis. This biofuel can be produced from agricultural biomass such as corn or agricultural residues. Production of butanol from agricultural biomass or renewable resources is essential for becoming independent of foreign oil/fuel. While production of this biofuel from biomass is an essential step, there is another challenge that must be met. The reader is informed that recovery of this biofuel from liquid mixture is energy intensive and for that reason alternative energy efficient process/es should be investigated. For these investigations, we studied simultaneous recovery of this biofuel by application of vacuum, a simple technique. By this process, recovery of butanol was found to be efficient as it can be performed at fermentation temperature, and the rate of butanol removal is faster than its production in the fermentation broth. It is expected that the developed method would help recover butanol from the broth efficiently thus benefiting the biofuel industry, U.S. public, and the farmers.

Technical Abstract: Simultaneous acetone butanol ethanol (ABE) fermentation by Clostridium beijerinckii 260 and in situ product recovery was investigated using a vacuum process operated in two modes: continuous and intermittent. Integrated batch fermentations and ABE recovery were conducted at 37 deg C using a 14-L bioreactor (7.0 L reaction volume) containing initial substrate (glucose) concentration of 60 g/L. The bioreactor was connected in series with a condensation system and vacuum pump. Vacuum was operated continuously or intermittently with 1.5 h vacuum sessions spaced by 4, 6, and 8 h intervals. Whereas a control ABE fermentation experiment was characterized by incomplete glucose utilization and premature termination of the fermentation due to butanol toxicity to C. beijerinckii P260, ABE fermentation and in situ recovery by both continuous and intermittent vacuum modes resulted in complete utilization of glucose, greater productivity, cell growth, and concentrated ABE stream. These results demonstrate that vacuum technology can be applied to integrated ABE fermentation and recovery even though the boiling point of butanol is greater than that of water.