State Key Laboratory of Pulp and Paper Engineering, South China University of Technology, Guangzhou, 510641, China.
Biotechnol Adv. 2010 Sep-Oct;28(5):613-9. doi: 10.1016/j.biotechadv.2010.05.010. Epub 2010 May 15.
Microcrystalline cellulose (MCC) was pretreated with phosphoric acid at 323K for 10h. X-ray diffraction (XRD) and Atomic Force Microscope (AFM) analyses revealed that the fiber surface morphology of pretreated MCC (P-MCC) were uneven and rough with the crystalline diffraction peaks of P-MCC decreased to a distinct range. The X-ray Photoelectron Spectroscopy (XPS) analysis showed that the uneven and rough surface of P-MCC could enhance the adsorption of cellulose to the molecular surface of cellulose, which is one of the key factors affecting enzymatic hydrolysis of cellulose. A reversible first order kinetics was employed to describe the adsorption kinetics of cellulase to MCC and P-MCC, and the adsorption rate constants of MCC and P-MCC were found to be 0.016, 0.024, 0.041, and 0.095, 0.149, 0.218min(-1), respectively at 278K, 293K and 308K. The activation energies of MCC and P-MCC hydrolysis reactions were found to be 22.257 and 19.721kJ mol(-1). The major hydrolysis products of MCC and P-MCC were cellobiose and glucose. Hydrolysis of MCC for 120h resulted in yields of glucose (7.21%), cellobiose (13.16%) and total sugars (20.37%). However, after the pretreatment with phosphoric acid, the corresponding sugar yields resulted from enzymatic hydrolysis of P-MCC were increased to 24.10%, 41.42%, and 65.52%; respectively, which were 3.34, 3.15, and 3.22 times of the sugars yields from enzymatic hydrolysis of MCC.
微晶纤维素（MCC）用磷酸在 323K 下预处理 10 小时。X 射线衍射（XRD）和原子力显微镜（AFM）分析表明，预处理 MCC（P-MCC）的纤维表面形貌不均匀且粗糙，P-MCC 的结晶衍射峰减少到明显范围。X 射线光电子能谱（XPS）分析表明，P-MCC 的不均匀和粗糙表面可以增强纤维素对纤维素分子表面的吸附，这是影响纤维素酶解的关键因素之一。采用可逆一级动力学描述了纤维素酶对 MCC 和 P-MCC 的吸附动力学，发现 MCC 和 P-MCC 的吸附速率常数分别为 0.016、0.024、0.041 和 0.095、0.149、0.218min(-1)，分别在 278K、293K 和 308K 下。发现 MCC 和 P-MCC 水解反应的活化能分别为 22.257 和 19.721kJ mol(-1)。MCC 和 P-MCC 的主要水解产物为纤维二糖和葡萄糖。MCC 水解 120h 后，葡萄糖（7.21%）、纤维二糖（13.16%）和总糖（20.37%）的产率。然而，用磷酸预处理后，P-MCC 酶解的相应糖产率分别提高到 24.10%、41.42%和 65.52%；分别是 MCC 酶解糖产率的 3.34、3.15 和 3.22 倍。
