Lignin is one of the major components in all lignocellulosic materials and it is an important factor in limiting the enzymatic hydrolysis of biomass. Numerous studies have shown an inverse correlation between the lignin content and the rate of biomass hydrolysis. The mechanisms of lignin interference in enzymatic hydrolysis are related to the structure of the lignocelluloses and to the properties of the enzymes. Lignin appears to limit the hydrolysis by creating a physical barrier restricting the access of the enzymes to carbohydrate polymers. On the other hand adsorption of the enzymes on lignin surfaces has been shown to be a major contributor in the inhibition of the hydrolysis. Often, binding of enzymes onto lignin is considered to take place mainly via hydrophobic interactions. However, due to the complex structure of lignin-rich hydrolysis residues, adsorption is likely to occur by several simultaneous and competitive mechanisms. Relatively little is still understood about the binding mechanisms and factors affecting on the binding of the enzymes on lignin.
The paper will describe adsorption of Trichodema reesei cellulase mixtures and monocomponents onto different lignins isolated from relevant technical feedstocks. The adsorption phenomenon is approached by studying competitive versus non-competitive adsorption of cellulase activities on lignins and impacts of isolation methods on lignin reactivity.