Chelator production and cellobiose dehydrogenase activity of wood inhabiting fungi

IRG/WP 00-10363

Weihong Qi, J Jellison

Multiple components have been postulated to be involved in the Fenton-based biological degradation of wood by brown rot fungi. Chelators have been implicated in essential iron reduction steps. Cellobiose dehydrogenase activity and quinone reducing activity have also been implicated in brown rot biodegradation. When biochelator production by three white rot fungi, three brown rot fungi and three wood inhabiting non-degradative fungi, was examined, all nine species produced chelating compounds. The chemical characteristics and iron-reducing ability of the chelators produced varied, however, with the brown rot fungi producing predominately phenolate vs. hydroxamate chelators. Of the species examined, the brown rot fungus Fomitopsis pinicola produced chelators with the greatest reductive ability. This fungus has also been observed to exhibit the ability to accumulate high levels of iron in soil block assays. When liquid cultures of Phanaerochaete chrysosporium (white rot fungus), Gloeophyllum trabeum (brown rot fungus) and Trichoderma viride (non-degradative wood inhabitant) were examined over a four week period, all three replicates of the three fungi showed measurable levels of cellobiose dehydrogenase activity. Similar results were seen when quinone-reducing activity was monitored, with specific activity being greatest in T. viride. Trichoderma can be shown to produce iron-reducing chelators, cellobiose dehydrogenase activity and quinone reducing activity along with the previously reported ability to produce large amounts of cellulase and other degradative enzymes. It is interesting that Trichoderma possesses so many of the components of a cellulose degrading system, yet is not associated with the rapid strength losses seen when wood is attacked by brown rot fungi.


Conference: 00-05-14/19 Kona, Hawaii, USA

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