An alcohol oxidase of Phanerochaete chrysosporium with a distinct glycerol oxidase activity

•An alcohol oxidase of Phanerochaete chrysosporium with a distinct glycerol oxidase side-activity.•Several AOX are known from fungi, but so far no AOX has been published which is able to oxidize glycerol.•The present AOX from P. chrysosporium is the first AOX accepting both, small monovalent alcohols and glycerol.•The green oxidant hydrogen peroxide could be generated from industrial side-streams of glycerol.

An intracellular alcohol oxidase (AOX) was isolated from the white-rot basidiomycete Phanerochaete chrysosporium (Pch), grown on l-lactate induction medium, and purified to electrophoretic homogeneity. The dimeric protein consisted of two identical 75 kDa subunits. The open reading frame of 1,956 bp resulted in a monomer consisting of 651 amino acids. The enzyme showed a pI at 5.4, a pH optimum of 9, a temperature optimum at 50 °C, possessed putative conserved domains of the GMC superfamily, a FAD binding domain, and showed up to 86% homology to alcohol oxidase sequences of Gloeophyllum trabeum and Coprinopsis cinerea. As was shown for the first time for an AOX from a basidiomycete, not only methanol, but also lower primary alcohols and glycerol were accepted as substrates. An assay based on aldehyde dehydrogenase confirmed d-glyceraldehyde as the product of the reaction. A bioprocess based on this enzyme could alleviate the problems associated with the huge side-stream of glycerol occurring during the manufacture of biodiesel, yielding the green oxidant hydrogen peroxide.