Hydrolysis of cellulose and wood powder treated with DMDHEU by a hydrolase enzyme complex, Fenton's reagent, and in a liquid culture of Trametes versicolor

Cellulose was treated with various concentrations of 1,3-dimethylol-4,5-dihydroxyethylene urea (DMDHEU) to obtain different DMDHEU contents in the cellulose preparation. The release of sugars due to hydrolysis by a cellulase enzyme complex clearly decreased with increasing DMDHEU content. When the cellulose preparation with the highest DMDHEU content was subjected to pretreatment with Fenton's reagent (Fe2+, H2O2), the sugar release increased 4.5-fold. Incubation of modified cellulose with only H2O2 did not increase sugar release by cellulase. Compared to cellulose, the sugar release from milled wood powder induced by cellulase was very low but still decreased due to treatment with DMDHEU. Sole incubation of wood powder with Fenton's reagent did barely cause more sugar release compared to the storage of wood powder in buffer, but when the pretreated wood was incubated with cellulase the sugar release was higher than without pretreatment. Release of sugar from untreated cellulose in liquid cultures of the white-rot fungus Trametes versicolor was detected after 7 days and increased linearly with incubation time. Sugar release from DMDHEU-treated cellulose was much lower and was not detectable before 21 days of incubation. Total protein content in the cultures was low, but was slightly higher in the cultures of untreated cellulose. Laccase activity was not different in the presence of untreated and DMDHEU-treated cellulose after 7 and 14 days, but increased with increasing DMDHEU content after 21 and 28 days.