Manganese deficiency can replace high oxygen levels needed for lignin peroxidase formation by Phanerochaete chrysosporium

The combined effects of Mn and oxygen on lignin peroxidase (LIP) activity a nd isozyme composition in Phanerochaete chrysosporium were studied by using shallow stationary cultures grown in the presence of limited or excess N. When no Mn was added, LIP, was formed in both N-limited and N-excess cultur es exposed to air, but no LIP activity was observed at Mn concentrations gr eater than 13 mg/liter. In oxygen-flushed, N-excess cultures, LIP was forme d at all Mn concentrations, and the peak LIP activity values in the extrace llular fluid were nearly identical in the presence of Mn concentrations ran ging from 3 to 1,500 mg/liter. When the availability of oxygen to cultures exposed to air was increased by growing the fungus under nonimmersed liquid conditions, higher levels of Mn were needed to suppress LIP formation comp ared with the levels needed in shallow stationary cultures. The composition of LIP isozymes was affected by the levels of N and Mn. Addition of veratr yl alcohol to cultures exposed to air did not eliminate the suppressive eff ect of Mn on LIP formation. A deficiency of Mn in N-excess cultures resulte d in lower biomass and a lower rate of glucose consumption than in the pres ence of Mn. In addition, almost no activity of the antioxidant enzyme Mn su peroxide dismutase was observed in Mn-deficient, N-excess cultures, but the activity of this enzyme increased as the Mn concentration increased from 3 to 13 mg/liter. No Zn/Cu superoxide dismutase activity was observed in N-e xcess cultures regardless of the Mn concentration.