Biodegradative mechanism of the brown rot basidiomycete Gloeophyllum trabeum: evidence for an extracellular hydroquinone-driven fenton reaction.
We have identified key components of the extracellular 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 metabolite, 2,5-dimethoxy-1,4-benzoquinone, and reduced it to 2,5-dimethoxyhydroquinone. In the presence of 2,5-dimethoxy-1,4-benzoquinone, the fungus also reduced extracellular Fe3+ to Fe2+ and produced extracellular H2O2. Fe3+ reduction and H2O2 formation both resulted from a direct, non-enzymatic reaction between 2,5-dimethoxyhydroquinone and Fe3+. Polyethylene glycol depolymerization by G. trabeum required both 2,5-dimethoxy-1,4-benzoquinone and Fe3+ 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 lignocellulose.
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Institute for Microbial and Biochemical Technology, USDA Forest Products Laboratory, Madison, WI 53705, USA.
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D000975:Antioxidants / Q000378:metabolism; D001487:Basidiomycota / Q000378:metabolism*; D001673:Biodegradation, Environmental; D005110:Extracellular Space / Q000378:metabolism; D006873:Hydroquinones / Q000378:metabolism*; D010084:Oxidation-Reduction; D011092:Polyethylene Glycols / Q000378:metabolism*
D000975:Antioxidants; D006873:Hydroquinones; D011092:Polyethylene Glycols; C031927:hydroquinone