Tu Maobing, Zhang Xiao, Paice Mike, MacFarlane Paul, Saddler Jack N
School of Forestry and Wildlife Sciences, Auburn University, Auburn, AL 36849-5418, USA.
Bioresour Technol. 2009 Dec;100(24):6407-15. doi: 10.1016/j.biortech.2009.06.108. Epub 2009 Jul 25.
Despite recent improvement in cellulase enzymes properties, the high cost associated with the hydrolysis step remains a major impediment to the commercialization of full-scale lignocellulose-to-ethanol bioconversion process. As part of a research effort to develop a commercial process for bioconversion of softwood residues, we have examined the potential for recycling enzymes during the hydrolysis of mixed softwood substrate pretreated by organosolv process. We have used response surface methodology to determine the optimal temperature, pH, ionic strength, and surfactant (Tween 80) concentration for maximizing the recovery of bound protein and enzyme activity from the residual substrates after hydrolysis. Data analysis showed that the temperature, pH and surfactant concentration were the major factors governing enzyme desorption from residual substrate. The optimized conditions were temperature 44.4 degrees C, pH 5.3 and 0.5% Tween 80. The optimal conditions significantly increased the hydrolysis yield by 25% after three rounds of hydrolysis. This bound enzyme desorption combining with free enzyme re-adsorption is a potential method to recover cellulase enzymes and reduce the cost of enzymatic hydrolysis.
尽管纤维素酶的性能最近有所改善，但水解步骤的高成本仍然是大规模木质纤维素制乙醇生物转化工艺商业化的主要障碍。作为开发软木残渣生物转化商业工艺研究工作的一部分，我们研究了在有机溶剂法预处理的混合软木底物水解过程中回收酶的潜力。我们使用响应面方法来确定最佳温度、pH值、离子强度和表面活性剂（吐温80）浓度，以最大限度地从水解后的残余底物中回收结合蛋白和酶活性。数据分析表明，温度、pH值和表面活性剂浓度是控制酶从残余底物上解吸的主要因素。优化条件为温度44.4摄氏度、pH值5.3和0.5%吐温80。经过三轮水解后，最佳条件显著提高了25%的水解产率。这种结合酶解吸与游离酶再吸附是回收纤维素酶并降低酶水解成本的一种潜在方法。
