Butyric acid, a short chain carboxylic acid with diverse usages, is produced by Clostridia fermentation. In the industrial scale production of butyric acid, its separation and recovery from fermentation broth requires energy-intensive processes. To reduce the product recovery costs, it is necessary to convert butyric acid into a chemical with a much higher partition coefficient in the hydrophobic extractants than butyric acid. Butyl butyrate, with an excellent partition coefficient to tetradecane, can be produced by the enzymatic conversion of butyric acid via esterification. Moreover, butyl butyrate can be used as a valuable fuel source and additive in the food, cosmetic, and pharmaceutical industries. Novozyme 435, Candida antarctica lipase B immobilized on acrylic resin, and tetradecane were used as the enzyme and extractant, respectively. A high-pressure CO₂-facilitated reactor was used to temporarily drop the pH of the fermentation broth so that the enzymatic reaction could be activated. The in situ removal of butyric acid and simultaneous production of butyl butyrate were processed continuously during fermentation. To optimize the enzymatic reaction, it was necessary to maintain a temperature of 40°C at 50 bar and an optimal molar ratio of substrate. In the extractive fermentation, 11.6 g/L butyl butyrate was produced with a productivity of 0.77 g/L/h from butyrate produced through fermentation. This process is expected to be able to extract carboxylic acids with more diverse carbon lengths in ester form.

丁酸是梭状芽胞杆菌发酵产生的具有多种用途的短链羧酸。在工业规模的丁酸生产中，从发酵液中分离和回收丁酸需要消耗大量能量的过程。为了降低产品回收成本，有必要将丁酸转化为疏水萃取剂中的分配系数比丁酸高得多的化学物质。丁酸丁酸酯的分配系数极佳，可以通过酯化将丁酸进行酶促转化而制得。此外，丁酸丁酯可以用作食品，化妆品和制药行业中有价值的燃料来源和添加剂。南极假丝酵母Novozyme 435固定在丙烯酸树脂上的脂肪酶B和十四烷分别用作酶和提取剂。使用高压CO ₂促进的反应器暂时降低发酵液的pH，从而可以激活酶促反应。在原位除去丁酸和同时生产丁酸丁酯的均在发酵连续处理。为了优化酶促反应，必须将40°C的温度保持在50 bar，并保持最佳的底物摩尔比。在萃取发酵中，由发酵产生的丁酸酯产生11.6g / L的丁酸丁酯，生产率为0.77g / L / h。预期该方法能够以酯形式提取具有更多不同碳长度的羧酸。