The Role of Laccase from White Rot Fungi to Stress Conditions

Abstract

This study was performed in order to investigate the effect of selected xenobiotic compounds, such as different stress factors, Cd(II), Zn(II), Cu(II) and Mn(II) ions or some pro-oxidants: menadione, paraquat and hydrogen peroxide, on laccase activity with some white-rot fungi. Changes in laccase activity in the presence of natural fungicidals, the saponins from Medicago sativa roots, were also examined. The intro- duction of both metal ions and some pro-oxidants into the medium enhanced a multiple increase in extra- cellular laccase activity for the two fungal strains, Trametes versicolor and Abortiporus biennis. An nota- ble increase in laccase level had already appeared in the 36 hour by the treatment with oxidative stress fac- tors (menadion, paraquat and hydrogen peroxide), anti-fungal substance saponines as well as metal ions. The enhanced activity of laccase under heavy metal ions presence also suggests its important role in the fun- gal adaptation processes, what could be utilized to heavy metals containing waste materials. These strains of white-rot fungi could also be used to remove heavy metals from aqueous solutions by adsorbing the met- als on mycelium and to biodegrade various organic xenobiotics by extracellular laccase. The presence of harmful compounds in the medium which might appear lethal for other organisms arouses detoxification abilities of this fungal group by increasing extracellular discharge of ligninolytic enzymes, in particular lac- case. This offers extremely large possibilities for biotechnological use of white-rot fungi.