Optimization of manganese peroxidase and laccase production in the South American fungus Fomes sclerodermeus (Lév.) Cke.

Fomes sclerodermeus produces manganese peroxidase (MnP) and laccase as part of its ligninolytic system. A Doehlert experimental design was applied in order to find the optimum conditions for MnP and laccase production. The factors studied were Cu(2+), Mn(2+) and asparagine. The present model and data analysis allowed us not only to define optimal media for production of both laccase and MnP, but also to show the combined effects between the factors. MnP was strongly influenced by Mn(2+), which acts as an inducer. Under these conditions Cu(2+) negatively affected MnP activity. At 13 days of growth 0.75 U ml(-1) were produced in the optimized culture medium supplemented with 1 mM MnSO(4) and 4 g l(-1) asparagine. The laccase titer under optimized conditions reached maximum values at 16 days of growth: 13.5 U ml(-1) in the presence of 0.2 mM CuSO(4), 0.4 mM MnSO(4) and 6 g l(-1) asparagine. Mn(2+) promoted production of both enzymes. There were important interactions among the nutrients evaluated, the most significant being those between Cu(2+) and asparagine.