Profiles of enzyme activities, production of oxalic acid, and Fe3+-reducing metabolites secreted by the Polyporales brown-rot species Fomitopsis pinicola

Fungi in the Basidiomycota order Polyporales, class Agaricomycetes, are specified to the lifestyle of decomposition of dead wood and woody debris, and thereby, are crucial players in degradation of organic matter and cycling of carbon in the forest ecosystems. Polyporales wood-decaying species comprise of both white-rot and brown-rot fungi, based on their mode of decomposition of compact wood and lignocelluloses. While the white-rot fungi are able to attack and decompose all the lignocellulose biopolymers, the brown-rot species mainly cause destruction of wood polysaccharides (cellulose and hemicelluloses) with minor modification of the lignin units. The biochemical mechanism of brown rot decay of wood is still unclear, and has been proposed to include a combination of non-enzymatic oxidation reactions and carbohydrate-active enzymes. Therefore, a combinatory approach is needed to dissect the fungal brown-rot processes. We studied the brown-rot species Fomitopsis pinicola, by following mycelial growth, production of carbohydrate-active enzymes and proteinases, and generation of metabolites together with Fenton reaction promoting Fe3+-reducing activity, for three months in submerged cultures.