Accumulation of heavy metals in the mycelium of Abortiporus biennis and their effect on oxalate oxidase activity.

Abortiporus biennis belongs to a basidiomycete fungi with the unique ability to degrade oxalate using enzyme oxalate oxidase. Oxalate oxidase (OXO) from Abortiporus biennis is an intracellular oxalic acid-induced enzyme, which catalyses the degradation of oxalic acid to carbon dioxide and hydrogen peroxide. OXO activity was stimulated by all the heavy metals tested (copper, manganese, lead and cadmium) after addition as water-soluble salts to A. biennis fungal cultures. Manganese ions stimulated OXO activity to the greatest extent among the tested metal ions. In the presence of manganese ions, an elevated concentration of oxalate was also detected in the fungal culture after 7 days of cultivation. The manganese, lead, and cadmium ions were accumulated by the A. biennis mycelium. Among them, lead was accumulated to a great extent. It was observed that the accumulation of lead ions occurred in the vicinity of the A. biennis hyphal cell wall.