Assessment of the Potential of Arthromyces Ramosus Peroxidase to Remove Phenol from Industrial Wastewaters

Abstract

The ability of Arthromyces ramosus peroxidase (ARP) to catalyze phenol removal from aqueous solution was investigated under a number of conditions both in the presence and in the absence of a protective additive, high molecular weight polyethylene glycol. The stoichiometry of phenol removal to peroxide consumption was observed to increase from 1.0 to 1.2 as initial phenol, peroxide and enzyme concentrations were increased. ARP was found to exhibit thermal stability comparable to that of HRP, but considerably less than that of SBP when incubated at pH 7.0 at temperatures between 35 and 55 °C. The activation energy was estimated to be 69 kJ mol−1. The benefit of using PEG to slow the rate of the permanent inactivation of ARP was demonstrated. Approximately 13.7 times less enzyme was required for a given phenol removal in the presence of excess PEG than was needed in its absence. ARP was found to be as efficient as SBP, but less efficient than HRP, at removing phenol at 25 °C and pH 7.0. Modeling suggested that the enzyme undergoes rapid and essentially irreversible inactivation in the presence of excess hydrogen peroxide. Spectral observation indicated that the inactive form of ARP produced in the presence of hydrogen peroxide was not solely compound III (a temporary inactivation), nor was it verdohaemoprotein (a permanent inactivation), as is the case when HRP undergoes inactivation by hydrogen peroxide.