3-62: Regulation of manganese peroxidase isozymes in Phanerochaete chrysosporium

The use of lignin degrading enzymes has been exemplified to degrade and metabolize lignin, as well as degrade recalcitrant oraganopollutants. Manganese peroxidase (MnP) (EC 1.11.1.13) catalyzes the chemical reaction 2Mn(II)+2H⁺+H₂O₂↔2Mn(III)+2H₂O in the presence of chelators. Current study is focused on the regulation of different MnP isozymes in Phanerochaete chrysosporium. The mnp expressions through reverse transcriptase-PCR in different carbon sources at various time points revealed the differential expression behavior of these isozymes. The significant expression was observed during five to seven days of fermentation. Analysis of extra- and intracellular peptide composition in selected medium showed the presence of four MnP isozymes. The study demonstrated the considerably higher MnP activities of 4,700 U/L with the selected carbon source in the presence of tween80 (T), nitriloacetate (N) and inorganic salts (IS). However, accumulation of intracellular MnPs was also observed in the fungal pellets during five to seven days which was consistent with the microscopic observations with an increased enzyme pockets within the mycelium. We speculate the crucial roles of membrane-bound transporters for an excretion of MnPs. We aim to find out these transporters whereas Ca²⁺ ions produced during the pelletization of fungus might play a role for their activation. Moreover, correlating the interconnections of T, N and IS in mnp expression, seven days culture showed the dependency of mnp-2 isozyme in T and IS and mnp-3 in N. However, the individual extracellular MnP and their quantification is an important issue. The significance of this study is the understanding of the mechanism of mnp expression regulation in P. chrysosporium.