Screening of Conditions for Manganese Peroxidase Production from White Rot Fungi (Pleurotus djamor)

Abstract

The need for alternative and environmentally friendly methods for waste clean-up has led to the use of enzymes in bioremediation. In this study, white rot fungi were isolated from decaying plant parts using standard microbiological and biochemical techniques. The isolated fungi were identified and screened using standard substrates (2, 6-DMP) to determine their capability to produce manganese peroxidase. Pure manganese peroxidase was achieved after four distinct purification phases. Crude extract of the homogenate proteins obtained through optimized submerged fermentation system were precipitated using ammonium sulfate. Ammonium sulfate used at 60% concentration at pH 4.5 precipitated proteins with highest Manganese peroxidase activity (322 U/mg). The precipitated proteins were desalted through dialysis for twelve hours with buffer exchange at interval of six hours and activity of 343.91 U/mg was recorded afterwards. DEAE-cellulose was used for the ion exchange purification of the dialyzed protein, NaCl gradients of 0.3-0.6 M was found to be best in washing off bound protein from the exchange resin and activity of 434.18 U/mg was recorded from the pooled fraction tubes. Sephadex G-100 was used for separation of the proteins into molecular sizes and weights. 2.8 purification folds of the enzyme were achieved after ion exchange (DEAE-cellulose) and gel filtration (sephadex G-100) with percentage yield of 2.20%. Specific activity of the enzyme increased to 602.00% after gel filtration. The partial purified enzyme was further characterized for determination of optimal pH (4.5), temperature (40 OC) and kinetic properties Km of 3.4 mM and Vmax of 250µmol/min.