ADSORPTION OF DIFFERENT LACCASES ON CELLULOSE AND LIGNIN SURFACES

The adsorption of Trametes hirsuta and Melanocarpus albomyces laccases on cellulose and lignin model substrates was studied by quartz crystal microbalance with dissipation, QCM-D. The laccase-treated surfaces were also analyzed by atomic force microscopy (AFM) and x-ray photoelectron spectroscopy (XPS). The laccases were found to adsorb at acidic and neutral pHs on both surfaces. The adsorbed amounts increased rather linearly with the change in dissipation when the lignin or cellulose was treated with T. hirsuta laccase. Higher adsorbed amounts were obtained using M. albomyces laccase. The adsorption of M. albomyces laccase on lignin was strongly dependent on pH. At low pH thin and rigid laccase layers were formed and the amount adsorbed was high, while at high pH the laccase layers formed were dissipative and loose and the amount adsorbed was low. A good correlation between the adsorbed amount of laccase and the surface nitrogen content was found. The adsorption of laccases made the surface structure of the cellulose and lignin substrates more granular