Relationship of Phenol Oxidase Activity and Hydroxyl-Radical Generation to Wood Degradation by White-Rot Basidiomycetes

Abstract

Wood degradation, phenol oxidase activity, and the generation of hydroxyl radicals were examined in cultures of eight basidiomycetes that are usually regarded as white-rot fungi. Six of the fungi degraded Japanese beech wood to a significant extent under the conditions used. These six basidiomycetes also had measurable phenol oxidase activity after 1wk in woodcontaining cultures. With two of the six fungi, phenol oxidase activity peaked after 1wk of incubation. One of the six fungi had the highest activity after 6wk. The other three fungi had relatively constant phenol oxidase activities throughout the 8 wk incubation period. The six basidiomycetes that significantly degraded Japanese beech wood also generated significant amounts of hydroxyl radicals in the wood-containing cultures. The combined production of phenol oxidase and hydroxyl radicals in intact cultures of the eight basidiomycetes correlated roughly with the degree of wood degradation in the cultures. Most of the hydroxyl radicals were produced by agents other than phenol oxidase in cultures of white-rot fungi.