Lignin degradation by Rigidoporus lignosus involves synergistic action of two oxidizing enzymes: Mn peroxidase and laccase

Abstract

In the course of in vitro lignin degradation, Rigidoporus lignosus, a white-rot Basidiomycete, excreted two oxidative enzymes into the culture medium: laccase and Mn peroxidase. The two enzymes were purified and their main properties studied. When isolated, neither the laccase nor the Mn peroxidase alone was able to solubilize the radioactive Hevea lignins efficiently in vitro. In contrast, when the two enzymes were added to the reaction medium at the same time, lignin solubilization was extensive: the laccase and the Mn peroxidase acted synergistically. In addition, other enzymes, such as glucose oxidase, could be involved in ligninolysis mechanisms. Indeed, in our in vitro system, glucose oxidase enhanced lignin solubilization probably by preventing the repolymerization of the radicals formed by the two oxidative enzymes.