Enzymatic degradation of tetracycline and oxytetracycline by crude manganese peroxidase prepared from Phanerochaete chrysosporium

Pharmaceuticals have been attracting increasing attention in recent years as emerging contaminants, of which the most frequently detected kind in various environments are antibiotics. In this study, crude manganese peroxidase (MnP) prepared from the Phanerochaete chrysosporium, a white rot fungi, was taken as a highly efficient biocatalyst to degrade tetracycline (TC) and oxytetracycline (OTC) which are widely used antibiotics. The results show that 72.5% of 50 mg/L of TC was degraded when added 40 U/L of MnP, while 84.3% of 50 mg/L of OTC was degraded with the same amount of the catalyst added, both within 4 h. The degradation rate was dependant on the pH and the temperature of the reaction system, and was likely sensitive to the concentration of H2O2. With the pH at 2.96-4.80, the temperature at 37-40 degrees C, the Mn2+ concentration higher than 0.1 mM and up to 0.4 mM, the H2O2 concentration of 0.2 mM, and the enzyme-substrate ratio above 2.0 U/mg, the degradation rate reached the highest. In addition, a separate series of experiments also show that the compensation of H2O2 during the reaction process could improve the degradation of TC by MnP. (C) 2010 Elsevier B.V. All rights reserved.