Application of enzymatic esterification under high pressure CO2 condition for in situ recovery of butyric acid from anaerobic fermentor

Butyric acid is a small fatty acid with diverse usages, and it is usually produced via petrochemical routes. Bacterial fermentation can be an alternative method for butyric acid production in light of the decrease in the petroleum. But the recovery of butyric acid from fermentation broth is energy intensive process. Butyric acid can be easily extracted by extractant when it is converted to be butyl butyrate throughout the enzymatic esterification. Novozym 435, Candida antarctica lipase B immobilized with acrylic resin, and tetradecane were used as the enzyme and extractant, respectively. The very high partition coefficient of butyl butyrate pulls the esterification toward the ester even at relatively low concentration of butyric acid. The high pressure CO₂-facilitated reactor was used to drop the pH of aqueous phase. The enzymatic reactions were carried out at 40℃ and 50 bar. In situ extraction through the enzymatic esterification could be applied to fermentation and The ester could be used as a final product, or hydrolyzed back to pure butyric acid. Throughout the enzymatic conversion of carboxylic acids to ester chemicals using high pressure CO₂-facilitated reactor, it is expected that more diverse carbon length of carboxylic acids can be extracted from the fermentation broth.