Evaluation of selected white-rot fungi for biosulfite pulping

Biosulfite pUlping of Eucalyptus grandis wood chips pretreated with ten strains of selected white-rot fungi was investigated. The biopulping efficiency was evaluated based on fungal pretreatment time (5, 7 and 10 days) and properties of biosulfite pulp (pulp yield, kappa number, brightness, alkali solubility SII) and SIX, and viscosity) in comparison to the controls. Pretreatment of eucalyptus wood chips with Ceriporiopsis subvermispora SS-3 in the absence of an additional carbon source for 10 days resulted in a substantial decrease in kappa number (by 29%) and increase in brightness (by 12%). On the other hand 5% of the pulp yield was lost, and both viscosity and alkali solubility (Sltl and SIX) were retained at levels comparable to the control. When the fungal incubation time was reduced to 5 days, a 5% reduction of kappa number, 11 % increase in brightness and no loss of pulp yield was observed. C. subvermispora SS-3 was therefore selected for further optimization studies of biosulfite pulping for dissolving pulp-directed manufacture.