固定化脂肪酶生物反应器催化合成乙酸正己酯
Catalyzed synthesis of hexyl acetate in immobilized lipase bioreactor
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摘要: 为提高非水相酶促合成食品添加剂乙酸正己酯的效率,以羧甲基纤维素为稳定剂,通过物理吸附,将假单胞菌脂肪酶Pseudomonas cepacia lipase固定在锥形瓶内壁上,制备成简易的生物反应器,并研究了其用于催化合成乙酸正己酯的动力学。结果表明,在反应器中,加入己醇与乙酸乙烯酯的混合液,并在37℃、150r/min下摇动,反应即开始;反应液倒出,则反应停止,无需过滤。反应7h,相对于酶粉,反应器中的固定化酶,可使反应转化率提高7倍,48h后,转化率达99%。经10次循环催化、共10d与有机相的接触,仍保留有52%的转酯活性;同样条件下,不添加羧甲基纤维素的固定化酶,仅有12.8%的活性。可见,这种反应器操作方便,能有效提高酶的非水活性和稳定性,适于催化非水相反应。Abstract: To efficiently improve lipase- catalyzed synthesis of food additive hexyl acetate in nonaqueous phase,a simple bioreactor was prepared by immobilizing Pseudomonas cepacia lipase on inner wall of conical flask via physical adsorption and with carboxymethyl cellulose as stabilizer,and used in catalyzed synthesis of hexyl acetate.Results showed that the reaction began after hexanol and vinyl acetate added in this reactor at 37℃ and150 r / min,and the reaction stopped once reaction mixture powered off it. Comparing with lipase power,the immobilized lipase in bioreactor could cause 7- fold increase in transesterification conversion rate of hexanol reacting with vinyl acetate after 7h.After 48 h,the conversion achieved more than 99%. Moreover,stability of lipase also was obviously strengthened for CMC- stabilized immobilization.After ten times of catalyzed recycles,total ten days of contacting with organic phase,CMC- stabilized immobilized lipase still kept 52% of transesterification activity.And under the same of conditions,water- modified immobilized lipase only left 12.8% of transesterification activity.It was obvious that the reactor was not only easy in operation but also available in enhancement of enzymatic activity and stability,fitting in nonaqueous catalysis.