Improved pretreatment of lignocellulosic biomass using enzymatically-generated peracetic acid
Release of sugars from lignocellulosic biomass is inefficient because lignin, an aromatic polymer, blocks access of enzymes to the sugar polymers. Pretreatments remove lignin and disrupt its structure, thereby enhancing sugar release. In previous work, enzymatically generated peracetic acid was used to pretreat aspen wood. This pretreatment removed 45% lignin and the subsequent saccharification released 97% of the sugars remaining after pretreatment. In this paper, the amount of enzyme needed is reduced ten fold using first, an improved enzyme variant that makes twice as much peracetic acid and second, a two-phase reaction to generate the peracetic acid, which allows enzyme reuse. In addition, the eight pretreatment cycles are reduced to only one by increasing the volume of peracetic acid solution and increasing the temperature to 60 oC and the reaction time to 6 h. For the pretreatment step, the weight ratio of peracetic acid to wood determines the amount of lignin removed.