Abstract: Effects of endo xylanase and xylosidase pretreatment on bleaching properties of wheat straw pulp have been investigated.Results show that brightness of bleached pulp with endo xylanase and xylosidase pretreatment is increased respectively by 2.5 and 1.9 percentages greater than that of control pulp, and strength of bleached pulps is better than that of control pulp.Endo xylanase and xylosidase acted synergistically on the pretreated wheat straw pulp before its bleaching.Brightness of bleached pulp with mixture of endo xylanase and xylosidase is increased respectively by 0.9 and 1.5 percentages greater than that with endo xylanase and xylosidase pretreatment.It is found that there were many pores in the surfaces and across sections of pulp with endo xylanase and xylosidase under electronic microscope, and pores of pulp with endo xylanase pretreatment were more and larger than those with xylosidase pretreatment. It is found that endo xylanase and xylosidase could not destroy pulp crystallinity by X-ray analysis.

Key words: endo-xylanase, xylosidase, wheat straw pulp, biobleaching