Department of Chemistry, Faculty of Science, Universiti Teknologi Malaysia, 81310 UTM Skudai, Johor, Malaysia.
Department of Biology, Faculty of Mathematics and Natural Sciences, University of Briwijaya, Jl Veteran, Malang, 65145, East Java, Indonesia.
Int J Biol Macromol. 2018 Jul 15;114:306-316. doi: 10.1016/j.ijbiomac.2018.03.095. Epub 2018 Mar 22.
The contribution of chitosan/nanocellulose (CS-NC) to the enzymatic activity of Candida rugosa lipase covalently bound on the surface of CS-NC (CRL/CS-NC) was investigated. Cellulosic material from oil palm frond leaves (OPFL) were bleached, alkaline treated and acid hydrolyzed to obtain the purified NC and used as nano-fillers in CS. XRD, Raman spectroscopy and optical fluorescence microscopic analyses revealed existence of strong hydrogen bonds between CS and the NC nanofillers. The CRLs were successfully conjugated to the surface of the CS-NC supports via imine bonds that occurred through a Schiff's based mechanism. Process parameters for the immobilization of CRL were assessed for factors temperature, concentration of glutaraldehyde and pH, to afford the highest enzyme activity to achieve maximum conversion of butyl butyrate within 3h of incubation. Conversion as high as 88% was reached under an optimized condition of 25°C, 0.3% glutaraldehyde concentration and buffer at pH7. Thermal stability of CRL/CS-NCs was 1.5-fold greater than that of free CRL, with biocatalysts reusability for up to 8 successive esterification cycles. This research provides a promising approach for expanding the use of NC from OPFL for enhancing enzyme activity in favour of an alternative eco-friendly means to synthesize butyl butyrate.
壳聚糖/纳米纤维素（CS-NC）对固定在 CS-NC 表面的 Candida rugosa 脂肪酶（CRL/CS-NC）的酶活性的贡献进行了研究。从油棕叶片（OPFL）中提取纤维素材料，经过漂白、碱性处理和酸水解，得到纯化的 NC，并将其用作 CS 的纳米填充物。XRD、拉曼光谱和光学荧光显微镜分析表明，CS 与 NC 纳米填充物之间存在强氢键。CRLs 通过希夫碱机制发生的亚胺键成功地结合到 CS-NC 载体的表面上。通过评估固定化 CRL 的过程参数，包括温度、戊二醛浓度和 pH 值，以获得最高的酶活性，从而在 3 小时的孵育时间内实现丁酸丁酯的最大转化率。在优化条件为 25°C、0.3%戊二醛浓度和 pH7 的缓冲液下，转化率高达 88%。CRL/CS-NCs 的热稳定性比游离 CRL 高 1.5 倍，生物催化剂在 8 次连续酯化循环中仍具有可重复使用性。这项研究为扩展 OPFL 中的 NC 的用途提供了一种有前途的方法，以提高酶活性，有利于替代环保的方法来合成丁酸丁酯。
