Abstract: In recent years there has been a growing interest in using xylanase(E.C. 3.2.1.8)in the pulping process.A strain library containing about 220 microbial xylanase producers isolated from a pulp and paper making factory was established.A novel bacterial alkali tolerant xylanase producer WXULI 11 and three fungal xylanase producers XY04B,XY07C and XY12D were screened from this library.The production conditions of these three fungal producers were investigated and the results showed that under the optimal conditions,XY04B and XY12D could produce xylanase at the level of 136.74 and 257.29IU/mL in 48h,while XY07C with 168.94IU/mL xylanase in 60h;their enzyme productivity were 68370,128654 and 67576IU/(L·d),respectively.

Key words: xylanase, strain library, fungus