Lignin-derived inhibition of monocomponent cellulases and a xylanase in the hydrolysis of lignocellulosics. (May 2017) - Kellock, Miriam
Highlights: The binding mechanisms of enzymes onto lignin thin films are enzyme specific. Of the studied enzymes, the hydrolysis yields of Tr Cel6A and Tr Cel7B were most affected by lignin. Soluble compounds from isolated lignin increased β-glucosidase activity up to 28%. Abstract: Non-productive enzyme binding onto lignin is the major inhibitory mechanism, which reduces hydrolysis rates and yields and prevents efficient enzyme recycling in the hydrolysis of lignocellulosics. The detailed mechanisms of binding are still poorly understood. Enzyme-lignin interactions were investigated by comparing the structural properties and binding behaviour of fungal monocomponent enzymes, cellobiohydrolases Tr Cel7A and Tr Cel6A, endoglucanases Tr Cel7B and Tr Cel5A, a xylanase Tr Xyn11 and a β-glucosidase An Cel3A, onto lignins isolated from steam pretreated spruce and wheat straw. The enzymes exhibited decreasing affinity onto lignin model films in the following order: Tr Cel7B > Tr Cel6A > Tr Cel5A > An Cel3A > Tr Cel7A > Tr Xyn11. As analysed in Avicel hydrolysis, Tr Cel6A and Tr Cel7B were most inhibited by lignin isolated from pretreated spruce. This could be partially explained by adsorption of the enzyme onto the lignin surface. Enzyme properties, such as enzyme surface charge, thermal stability or surface hydrophobicity could not alone explain the adsorption behaviour.