EXPERIMENTAL-ANALYSIS OF A PRODUCT INHIBITED FERMENTATION IN AN AQUEOUS 2-PHASED SYSTEM

Two aqueous two-phased sytems were investigated to determine their ability to reduce product inhibition in the acetone-butanol-ethanol (A-B-E) fermentation. In an attempt to avoid the high-cost of fractionated dextran, an industrial-grade dextran (DEX) and a hydroxylpropyl starch polymer, whose commercial name is Aquaphase PPT (APPT), were tested as the copolymer with polyethylene glycol (PEG) to form the two-phased fermentation broth. The two-phased fermentation performances in the DEX-PEG and APPT-PEG two-phase systems were compared to a single-phased conventional fermentation through a series of batch runs. Also, the effects of the phase forming polymers on Clostridium acetobutylicum were investigated. With the butanol partition coefficient of 1.3, which is defined as the concentration ratio of butanol in the continuous and dispersed phases, the butanol yield with the two-phased system was increased by 27% in comparison to the conventional fermentation.