SELECTIVE BIOSYNTHESIS OF XYLANASES WITH LOW CELLULASE CONTENT BY TRICHODERMA REESEI RUT C-30 AND APPLICATION IN THE PRETREATMENT OF WHEAT STRAW PULP

摘要

The effects of the carbon source,culture temperature,initial pH and carbon-to-nitrogen(C/N)ratio on the synthesis of xylanase and cellulase by Trichoderma reesei Rut C-30 were investigated.The results showed that enhancement of the xylanase activity to 186.93 IU/mL and,respectively,suppression of the cellulase activity to 0.156 IU/mL were possible,under the following conditions:cultivation time:6 days,initial pH:6,C/N ratio:7.2,36 °C in the first day of cultivation and 26 °C,respectively,for the last 5 days.A small amount of cellulase was found in the xylanase-aided bleaching action.In the xylanase pretreatment of pulp,the most suitable X/C ratio in xylanase was of 121,while brightness of the bleached pulp pretreated with xylanase increased by 4.2 SBD units relative to the control sample,at a chlorine dosage of 5%.The chlorine dosage could be reduced to 38% at the same final brightness,while the strength of xylanase pretreated and bleached pulp did not decrease,comparatively with the control pulp.