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The Polyporales phlebioid white rot fungus Phlebia radiata is efficient in decomposing the wood main components, and in producing ethanol from lignocelluloses and waste materials. Based to these qualifications, the fungus was adopted for design of a consolidated bioprocess method to convert wood waste materials into ethanol without pretreatments. Higher ethanol yield was aimed by introducing collaborative fungal cultivations including isolates of Saccharomyces cerevisiae, other yeasts, and a brown rot fungus. Various waste lignocellulose materials such as wheat and barley straw, recycled wood-fiber based core board, recycled construction waste wood, spruce saw dust, and birch wood were applied to represent wood and non-wood waste lignocellulose of different origin, chemical content and structure. In solid-state single cultivations with the white rot fungus P. radiata, both core board and barley straw turned out as suitable substrates for the consolidated bioprocess. Up to 32.4 ± 4.5 g/L of ethanol accumulated in the solid-state core board cultivation in 30 days whereas with barley straw, 7.0 ± 0.01 g/L of ethanol was obtained. Similar concentrations of ethanol were produced in increased-volume and higher gravity bioreactor cultivations without chemical, physical or enzymatic pretreatment. In all, our consolidated method adopting a white rot fungus is a promising and economic alternative for second generation bioethanol production from waste and residual lignocelluloses. [ABSTRACT FROM AUTHOR]

Basidiomycota fungi in the order Polyporales are specified to decomposition of dead wood and woody debris and thereby are crucial players in the degradation of organic matter and cycling of carbon in the forest ecosystems. Polyporales wood-decaying species comprise both white rot and brown rot fungi, based on their mode of wood decay. While the white rot fungi are able to attack and decompose all the lignocellulose biopolymers, the brown rot species mainly cause the destruction of wood polysaccharides, 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 nonenzymatic oxidation reactions and carbohydrateactive enzymes. Therefore, a linking approach is needed to dissect the fungal brown rot processes. We studied the brown rot Polyporales species Fomitopsis pinicola by following mycelial growth and enzyme activity patterns and generating metabolites together with Fenton-promoting Fe3+-reducing activity for 3 months in submerged cultures supplemented with spruce wood. Enzyme activities to degrade hemicellulose, cellulose, proteins, and chitin were produced by three Finnish isolates of F. pinicola. Substantial secretion of oxalic acid and a decrease in pH were notable. Aromatic compounds and metabolites were observed to accumulate in the fungal cultures, with some metabolites having Fe3+-reducing activity. Thus, F. pinicola demonstrates a pattern of strong mycelial growth leading to the active production of carbohydrate- and protein-active enzymes, together with the promotion of Fenton biochemistry. Our findings point to fungal species-level "fine-tuning" and variations in the biochemical reactions leading to the brown rot type of wood decay. IMPORTANCE Fomitopsis pinicola is a common fungal species in boreal and temperate forests in the Northern Hemisphere encountered as a wood-colonizing saprotroph and tree pathogen, causing a severe brown rot type of wood degradation. However, its lignocellulose-decomposing mechanisms have remained undiscovered. Our approach was to explore both the enzymatic activities and nonenzymatic Fenton reaction-promoting activities (Fe3+ reduction and metabolite production) by cultivating three isolates of F. pinicola in wood-supplemented cultures. Our findings on the simultaneous production of versatile enzyme activities, including those of endoglucanase, xylanase, β-glucosidase, chitinase, and acid peptidase, together with generation of low pH, accumulation of oxalic acid, and Fe3+-reducing metabolites, increase the variations of fungal brown rot decay mechanisms. Furthermore, these findings will aid us in revealing the wood decay proteomic, transcriptomic, and metabolic activities of this ecologically important forest fungal species. [ABSTRACT FROM AUTHOR]