CHARACTERS OF METAL ADSORPTION BY AM FUNGAL MYCELIUM

Using fungal biomass recovered from compartmented glass bead cultivation system, Zn, Cd and Mn binding capacity of arbuscular mycorrhizal fungi were characterized in pH buffering solutions. Results indicated that fungal mycelium have significantly different binding capacity for different metals, the strongest is for Cd, followed by Zn, and the least for Mn. Under the current experimental conditions, the fungi could adsorb Mn, Zn and Cd up to 1.6%, 2.8% and 13.3% dry biomass respectively. However, most of the adsorbed Cd2+ could be exchanged by Ca2+. In addition, comparison on Cd adsorption by non-mycorrhizal and mycorrhizal roots demonstrated that mycorrhizal colonization changed adsorption characteristics of plant roots. Compared with non-mycorrhizal roots, mycorrhizal roots have higher CEC and stronger Cd binding capacity. Results from this study provided direct evidences for enhanced metal binding capacity of plant roots colonized by arbuscular mycorrhizal fungi.