Butyric acid production by Clostridium butyricum with integrated extraction and pertraction

The properties of an organic phase (Hostarex (20% w/w) in oleylalcohol) for extractive and pertractive fermentative production of butyric acid by Clos tridium butyricum were investigated and the ability of this organic phase t o be used in the fermentation process was established. The distribution coe fficient of butyric acid between water and the organic phase could be incre ased up to 13 in diluted solutions but decreased to 3.0 with an increase of pH up to 5.2 (pH of the fermentation process). The kinetics of direct extr action of butyric acid during both extraction and pertraction were two and three times, respectively higher than the reverse processes. Reverse stripp ing was faster, but remained slower than direct stripping. These results de monstrated that both extraction and pertraction could be successfully joine d with fermentation. An increase of total butyric acid concentration, from 7.3 g l(-1) in the control to 10.0 g l(-1) in extractive fermentation and t o 20.0 g l(-1) in pertractive fermentation and concurrent increases of yiel d of butyric acid from 0.24 g g(-1) in the control up to 0.30 g g(-1) in pe rtractive fermentation, showed the great possibility of successful integrat ion of these separation processes with fermentative production of butyric a cid by C. butyricum. (C) 1999 Elsevier Science Ltd. All rights reserved.