Laccase-based pretreatment to delignify and improve the saccharification of sugarcane bagasse and straw

Abstract

This work demonstrates the ability of an enzymatic pretreatment, based on the laccase from Pycnoporus cinnabarinus, and 1-­¿hydroxybenzotriazole (HBT) as mediator, to remove and/or modify lignin from sugarcane bagasse and straw residues, improving their subsequent saccharification. Up to 27% and 31% decrease of relative lignin content in ground sugarcane bagasse and straw, respectively, were achieved by the laccase-­¿mediator pretreatment followed by alkaline peroxide extraction. Moreover, the lignin removals directly correlated with improvements in enzymatic saccharification, increasing glucose releases around 39% and 46% for bagasse and straw, respectively, compared with the corresponding controls. Furthermore, the structural modifications produced in the lignin polymer of these sugarcane feedstocks during the enzymatic treatment were analyzed ¿in situ¿ by two-­¿dimensional nuclear magnetic resonance (2D-­NMR) at the gel state, which provided useful information regarding the lignin degradation mechanism.