非离子表面活性剂对木质纤维素酶解的促进作用

摘要

Low specific activity,high enzymatic loading and easy acitivity losing of cellulose enzyme have become bottlenecks for bioprocessing the lignocellulosic biomass into bioenergy and bioproducts.In this work,non-ionic surfactants were added to reduce the enzymatic loadings.Its effect on the hydrolysis of lignocelluloses was also studied.Experimental results showed that the non-ionic surfactant helped to enhance the hydrolysis of lignocellulose with 0.5% addition.With the addition of Tween-80 and PEG6000,Glucose produced from enzymatic hydrolysis of atmospheric glycerol pretreated wheat straw increased approximately 20%.The non-ionic surfactant also had a positive impact on the enzymatic hydrolysis of cellulosic biomass with less lignin and even no lignin.The glucose outputs from the filter paper and avicel increased almost by 90% and 70%—80%,respectively.The addition of non-ionic surfactants provided a higher diffusion coefficient k for enzymatic hydrolysis system,increased reaction efficiency in heterogeneous phase,and made a significantly lower Km in enzymatic reaction dynamics,therefore remarkably enhanced the affinity of substrates on cellulase.%纤维素酶单位酶活力较低、酶用量较高及酶自身易失活等因素依然是木质纤维素工业生产能源和生物基产品的瓶颈性问题。本文尝试在木质纤维素基质水解时添加一些非离子型表面活性剂以减少纤维素酶用量,并对这些非离子型表面活性剂促进酶解效率提高的原因进行了初步探讨。研究发现,添加非离子性表面活性剂能提高木质纤维素的酶解,添加浓度为0.05 g/g底物,常压甘油自催化预处理麦草经过添加两种非离子表面活性剂Tween-80和PEG 6000后葡萄糖产量分别可提高20%左右;非离子表面活性剂对不含木质素的原料酶解产糖也有较大的提高,以滤纸为底物时葡萄糖产量提高近90%,以微晶纤维素为底物时分别提高70%以上;添加非离子表面活性剂使得酶解体系中扩散系数k升高,异相反应效率提高,酶促反应动力学Km值明显减小,显著提高底物对纤维素酶的亲和力。