Characterization of Laccase Adsorption on Lignocellulosic Biomasses

Biorefinery is a valid alternative to fossil-based processes through the transformation of lignocellulosic biomasses (LB) into a spectrum of chemicals and biofuels (Cherubini, 2010). The sugar-based platform consists of I) one or more biomass pretreatments aimed at modifying/removing lignin; II) cellulose and hemicellulose enzymatic hydrolysis; III) the fermentation of the released pentose and hexose sugars. Pretreatment of lignocellulosic biomass is a key step. Biochemical pretreatments may be the best alternative in terms of process sustainability. Laccases – multicopper oxidoreductases - are among the most proposed enzymes for this purpose. The present study reports the adsorption of a recombinant fungal laccase - PoxA1b, previously proposed for the delignification of several LBs - on coffee silverskin and Cardoon stalks. The milled and sieved biomasses (0.5 - 1 mm) were dispersed in PoxA1b solutions at several initial enzyme concentrations. The preliminary characterization pointed out two occurring phenomena: the adsorption of the laccases on the biomass surface, and its effect on the further adsorption of cellulases in the enzymatic hydrolysis step. Perspectives on future studies include tuning the adsorption-related phenomena and maximising the impact of the biochemical pretreatments in the delignification of LBs for biorefinery purposes.