Effect of lignin chemistry on non-productive enzyme adsorption in the enzymatic hydrolysis of lignocellulose

Lignin is an inhibitory compound in the enzymatic hydrolysis of lignocellulosic feedstocks. Non-productive enzyme adsorption onto lignin and subsequent enzyme inactivation is a major inhibitory mechanism that increases the enzyme dosage and thus the costs, it also restricts enzyme recycling especially with softwood feedstocks. The underlying mechanisms causing non-productive enzyme adsorption have remained mostly unsolved. This paper describes interactions of the major Trichoderma reesei cellobiohydrolase Cel7A and its
catalytic core domain with well-characterized isolated lignins from different botanical origin, namely from spruce and wheat straw. Both non-treated and steam explosion (SE) pretreated lignocellulosic materials were used for lignin isolation and subsequent preparation of ultrathin lignin films for enzyme adsorption studies. We applied quartz crystal microbalance (QCM) technique for real-time monitoring of enzyme adsorption onto the different lignin films. Interestingly, more enzyme was bound onto the lignin films prepared of steam pretreated materials, whereas botanical origin of lignin had only a minor effect on enzyme binding.