Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Simultaneous acetone butanol ethanol (ABE) fermentation by Clostridium beijerinckii P260 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 degrees C using a 14-L bioreactor (7.0 L fermentation 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 applied continuously or intermittently with 1.5 h vacuum sessions separated by 4, 6, and 8 h intervals. A control ABE fermentation experiment was characterized by incomplete glucose utilization due to butanol toxicity to C. beijerinckii P260, while fermentation coupled with in situ recovery by both continuous and intermittent vacuum modes resulted in complete utilization of glucose, greater productivity, improved cell growth, and concentrated recovered 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. Biotechnol. Bioeng. 2011;108: 1757-1765. (C) 2011 Wiley Periodicals, Inc.108817571765US Department of Transportation (USDOT) [GRT00012344]Northeast Sun grant Initiative [GRT00012344]Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Ohio BioProducts Innovation Center (OBIC) OSUFundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)US Department of Transportation (USDOT) [GRT00012344]Northeast Sun grant Initiative [GRT00012344]FAPESP [2007/00341-1]