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首页> 外文期刊>Bioprocess and Biosystems Engineering >Kinetic and thermodynamic studies on the enzymatic synthesis of wax ester catalyzed by lipase immobilized on glutaraldehyde-activated rice husk particles
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Kinetic and thermodynamic studies on the enzymatic synthesis of wax ester catalyzed by lipase immobilized on glutaraldehyde-activated rice husk particles

机译：固定在戊二醛活化的稻壳颗粒上的脂肪酶催化合成蜡酯的动力学和热力学研究

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摘要

Commercial lipase from Thermomyces lanuginosus has been immobilized on glutaraldehyde-activated rice husk particles via covalent attachment. It was reached maximum immobilized protein concentration of 27.5 +/- 1.8 mg g(-1) of dry support using the initial protein loading of 40 mg g(-1) of support. The immobilized biocatalyst was used to synthesize cetyl oleate (wax ester) via direct esterification of oleic acid and cetyl alcohol. The influence of relevant factors on ester synthesis, such as reaction temperature, biocatalyst concentration, presence or lack of hydrophobic organic solvents, acid:alcohol molar ratio, and reaction time has been evaluated. The experimental data were well fitted to a second-order reversible kinetic model to determine apparent kinetic constants. Thermodynamic studies have revealed that the reaction was a spontaneous and endothermic process. Under optimal experimental conditions, it was observed maximum ester conversion of 90.2 +/- 0.6% in 9 h of reaction time in hexane medium using 1 M of each reactant (cetyl alcohol and oleic acid), at 50 A degrees C and biocatalyst concentration of 15% m/v of reaction mixture. Similar conversion (91.5 +/- 0.8%) in a solvent-free system was also obtained within 24 h of reaction. The biocatalyst retained 85% of its initial activity after 12 cycles within 9 h of reaction in hexane medium. The physicochemical properties of purified ester have been determined in accordance with ASTM standards. The results indicate that the prepared biocatalyst has great potential for wax ester synthesis due to its satisfactory catalytic activity and operational stability.
机译：来自羊毛嗜热丝菌的商业脂肪酶已通过共价连接固定在戊二醛激活的稻壳颗粒上。使用40 mg g（-1）的初始蛋白质负载量，可以达到27.5 +/- 1.8 mg g（-1）的干燥支持物的最大固定蛋白质浓度。固定化的生物催化剂用于通过油酸和十六醇的直接酯化反应合成十六烷基油酸酯（蜡酯）。已评估了相关因素对酯合成的影响，例如反应温度，生物催化剂浓度，是否存在疏水性有机溶剂，酸/醇摩尔比和反应时间。实验数据非常适合二阶可逆动力学模型，以确定表观动力学常数。热力学研究表明该反应是自发的吸热过程。在最佳实验条件下，使用1 M的每种反应物（鲸蜡醇和油酸），在50 A的温度下，在己烷介质中，反应时间为9 h，在9 h的反应时间内，最大酯转化率为90.2 +/- 0.6％。 15％m / v的反应混合物。在无溶剂系统中，反应24小时内也获得了相似的转化率（91.5 +/- 0.8％）。在己烷介质中反应9小时后的12个循环中，生物催化剂保留了其初始活性的85％。纯化酯的物理化学性质已经根据ASTM标准确定。结果表明，所制备的生物催化剂具有令人满意的催化活性和操作稳定性，具有很大的合成蜡酯的潜力。

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