Submitted to: World Journal of Microbiology and Biotechnology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/19/2003
Publication Date: 7/1/2003
Citation: Ezeji, T.C., Qureshi, N., Blaschek, H.P. 2003. Production of acetone, butanol, and ethanol by Clostridium beijerinckii BA101 and in situ recovery by gas stripping. World Journal of Microbiology and Biotechnology. 19:595-603. Interpretive Summary: Butanol, a superior liquid fuel to ethanol, can be produced from corn or agricultural biomass using Clostridium beijerinckii or C. acetobutylicum. The steps that are required for the production of this fuel include processing of agricultural biomass in preparation to the conversion (to butanol) by the above microorganisms, fermentation to butanol, followed by recovery. Butanol recovery is the most energy intensive process among the three steps. In order to reduce energy requirement in the recovery process, we used an energy efficient process for butanol separation called gas stripping. By applying gas stripping to the butanol fermentation process, the efficiency of conversion was improved by 200% in addition to efficient recovery. The process would also reduce process streams, effluent (waste water) streams, and economize butanol production from corn. Butanol recovery by gas stripping is one of the most important techniques for this fuel production.
Technical Abstract: We examined the effect of gas-stripping on the in situ removal of acetone, butanol, and ethanol (ABE) from batch reactor fermentation broth. The mutant strain (Clostridium beijerinckii BA101) was not affected adversely by gas stripping. The presence of cells in the fermentation broth affected the selectivities of ABE. A considerable improvement in the productivity and yield was recorded in this work in comparison with the non-integrated process. In an integrated process of ABE fermentation-recovery using C. beijerinckii BA101, ABE productivities and yields were improved up to 200 and 118%, respectively, as compared to control batch fermentation data. In a batch reactor, C. beijerinckii BA101 utilized 45.4 gL**-1 glucose and produced 17.7 gL**-1 total ABE, while in the integrated process it utilized 161.7 gL**-1 glucose and produced total ABE of 75.9 gL**-1. In the integrated process, acids were completely converted to solvents when compared to the non-integrated process (batch fermentation), which contained residual acids at the end of fermentation. In situ removal of ABE by gas stripping has been reported to be one of the most important techniques of solvent removal. During these studies, we were able to maintain the ABE concentration in the fermentation broth below toxic levels.