Two stage fungal biopulping solubilizes lignocellulosic carbohydrates without supplemental enzymatic hydrolysis

• Novel wood decay fungi were examined for effects on carbohydrate solubility.
• Two stage treatments significantly increased the yield of enzymatic hydrolysis.
• Wild isolate treatments converted ca. 6.4–7.4% of biomass into soluble sugars.
• Sugars were released from fungal treated wood without hydrolysis treatment.

Novel applications of wood decay fungi were examined for effects on lignin and cellulose degradation, as well as carbohydrate solubility before and after treatment with commercial cellulose hydrolyzing enzymes. Pinus taeda wood chips were incubated with white (Ceriporiopsis subvermispora and Pleurotus ostreatus) and brown (Postia placenta and Fomitopsis cajanderi) rot fungi in an experimental matrix of single stage, simultaneous co-culture, and successive two-stage treatments. Two stage treatments significantly increased the yield of enzymatic hydrolysis by ca. 19% over controls utilizing industrial standard enzyme loading. Furthermore, novel two stage fungal colonization treatments using wild isolates of P. ostreatus and F. cajanderi directly converted ca. 6.4–7.4% of the bulk biomass into soluble reducing sugars without downstream enzymatic hydrolysis. This study is the first to report significant liberation of depolymerized reducing sugars from fungally-decayed wood chips without enzymatic hydrolysis treatment. This observation has significant potential utility in future fungal biopulping applications for lignocellulosic ethanol.