We have identified key components of the extra-cellular oxidative system that the brown rot fungus Gloeophyllum trabeum uses to degrade a recalcitrant polymer, polyethylene glycol, via hydrogen abstraction reactions. G. trabeum produced an extracellular metabolize, 2,5-dimethoxy-1,4-benzoquinone, and reduced it to 2,5-dimethoxyhydroquinone. In the presence of 2,5-dimethox-1,4-benzoquinone, the fungus also reduced extracellular Fe 3+ to Fe 2+ and produced extracelluar H2 O2 . Fe 3+ reduction and H2 O2 formation both resulted from a direct, non-enzymatic reaction between 2,5-dimethoxyhydroquinone and Fe 3+ .polyethylene glycol depolymerization by G. trabeum required both 2,5-dimethoxy-1,4-benzoquinone and Fe 3+ and was completely inhibited by catalase. These results provide evidence that G. trabeum uses a hydroquinone-driven Fenton reaction to cleave polyethylene glycol. We propose that similar reactions account for the ability of G. trabeum to attack lignocelluose.

Key words: Brown rot; Wood decay; Quinone redox cycling; Fenton reaction; Hydroxyl radical; Polyethylene glycol

Brown rot fungi are important contributors to the biomass recycling and soil fertility in forest ecosystems [1,2]. They also cause the most destructive type of decay in wooden structures [3]. These basidiomycetes are unusual in that they rapidly depolymerize the cellulose in wood without removing the sur-rounding lignin that normally prevents microbial attack. It is unlikely that the early steps in this process are enzymatic, because no known enzyme is small enough to penetrate sound wood [4]. Instead, brown rot fungi probably employ low mo-lecular weight (Mr ) degradative agents.

• biodeterioration : brown rot
• fungi and molds in buildings and their envelopes : brown rot

1. Flow Measurements
2. Prediction of indoor concentration of 0.5--4 mm particles of outdoor origin in an uninhabited apartment