Potential Use of Apple Polyphenol Oxidase for Bioremediation of Phenolic Contaminants

Abstract

Phenolic compounds, such as catechol, are released into the environment from a variety of industrial sources and they present a serious ecosystem burden. This work examined the possibility of using partially purified apple polyphenol oxidase (PPO) for bioremediation of phenolic contaminants. In order to optimize process conditions, the optimal pH and temperature for PPO activity were determined, while PPO affinity toward various phenols, as well as the effect of some salts and organic solvents which can be found in wastewaters, was used to confirm applicability of PPO in wastewater treatment. It was found that partially purified apple PPO shows maximal activity at pH 6.8 and 25 °C, but exhibits more than 85 % of its maximal activity in pH range from 5 to 8, and more than 90 % of activity in temperature range from 10 to 50 °C. PPO showed high affinity for various diphenols, but lack of affinity toward monophenols. Sodium tetraborate decahydrate moderately inhibited PPO activity, while exposure of PPO to the presence of organic solvents (φ = 5 %) caused 40 % loss in its activity. Catechol oxidation by PPO performed for just 5 min in a batch reactor at optimal process conditions resulted in 25 % conversion. Based on obtained data, it seems that partially purified apple PPO has reasonable potential in wastewater treatment.