Phenoloxidases are enzymes that are characterized by using different phenolic compounds as substrates and by having Cu atoms at their catalytic sites. In fungi, the production of phenoloxidases is related to obtaining nutrients from organic matter, the transformation of carbon during the carbon recycling, morphogenesis, delignification, sporulation, pigment production, fruiting body formation, and pathogenesis of plants. Regardless of their biological function, phenoloxidases have shown great potential in the field of the bioremediation, for instance, in the degradation of great quantity of xenobiotic compounds, such as dyes, hydroxylated polychlorinated biphenyls, polychlorophenols, and polycyclic aromatic hydrocarbons, endocrine-disrupting chemicals, insecticides, fungicides, and herbicides.

Given the relevance of phenoloxidases, this chapter describes some of the main characteristics of laccases and tyrosinases identified in fungi, as well as their applications in the degradation of toxic compounds present in the environment.