Effect of temperature on lignin-derived inhibition studied with three structurally different cellobiohydrolases.

Non-productive enzyme adsorption onto lignin inhibits enzymatic hydrolysis of lignocellulosic biomass. Three cellobiohydrolases, Trichoderma reesei Cel7A (TrCel7A) and two engineered fusion enzymes, with distinctive modular structures and temperature stabilities were employed to study the effect of temperature on inhibition arising from non-productive cellulase adsorption. The fusion enzymes, TeCel7A-CBM1 and TeCel7A-CBM3, were composed of a thermostable Talaromyces emersonii Cel7A (TeCel7A) catalytic domain fused to a carbohydrate-binding module (CBM) either from family 1 or from family 3. With all studied enzymes, increase in temperature was found to increase the inhibitory effect of supplemented lignin in the enzymatic hydrolysis of microcrystalline cellulose. However, for the different enzymes, lignin-derived inhibition emerged at different temperatures. Low binding onto lignin and thermostable structure were characteristic for the most lignin-tolerant enzyme, TeCel7A-CBM1, whereas TrCel7A was most susceptible to lignin especially at elevated temperature (55 °C).