demonstration of laccase-based removal of lignin from wood and non-wood plant feedstocks

the ability of trametes villosa laccase, in conjuction with 1-hydroxybenzotriazole (hbt) as mediator and alkaline extraction, to remove lignin was demonstrated during treatment of wood (eucalyptus globulus) and non-wood (pennisetum purpureum) feedstocks. at 50 u g⁻¹ laccase and 2.5% hbt concentration, 48% and 32% of the eucalyptus and pennisetum lignin were removed, respectively. two-dimensional nuclear magnetic resonance of the feedstocks, swollen in dimethylsulfoxide-d6, revealed the removal of p-hydroxyphenyl, guaiacyl and syringyl lignin units and aliphatic (mainly β-o-4′-linked) side-chains of lignin, and a moderate removal of p-coumaric acid (present in pennisetum) without a substantial change in polysaccharide cross-signals. the enzymatic pretreatment (at 25 u g⁻¹) of eucalyptus and pennisetum feedstocks increased the glucose (by 61% and 12% in 72 h) and ethanol (by 4 and 2 g l⁻¹ in 17 h) yields from both lignocellulosic materials, respectively, as compared to those without enzyme treatment.