An improved method to evaluate the o-diphenol oxidase activity of soil

Phenolic compounds are intermediary transformation products of many naturally occurring substances and synthetic chemicals, including crop residues, organic wastes, pesticides and industrial products. They are suitable substrates for the phenolases and peroxidases produced by the soil microflora. Although measurement of the enzymatic oxidation of phenolic compounds is an important measure of the soil microfloraʹs capacity to degrade potentially recalcitrant organics, the proposed methods to perform this measurement are few and questionable. In this paper a new, reliable and simple method to measure the o-diphenol oxidase activity in whole soil sample is proposed. The method is based on a spectrophotometric determination of a red compound (4-(N-proline)-o-benzoquinone) developed from enzymatic oxidation of catechol in the presence of proline.