STUDIES ON XYLANASE PRODUCTION BY ASPERGILLUS CLAVATUS 22
Liu Yueying Zheng Zhonghui Fu Yuxiao Yang Jinghui(Department of Biology, Xiamen University, Furjian Xiamen 361005)
A high xylanase producing strain 22 of Aspergillus clavatus was screened from 105 strains of molds and yeasts. The suitable medium consisted of (g/L): bagasse hemicellulose 30, NH_4NO_3 5, yeast extract 5, wheat bran 10, Tween 80 1 and a small quantity of other minerals; initial pH 5.5. Theoptimalsporeinoculumwas4.9X10~6spores/ml (final concentration). Theactivity of xylanase was as high as 335.9 U/ml in shake-flask experiment at 28℃ for 72 h. The optimal temperature and pH for xylanase reaction were 50℃ and pH 4.8. 72.6% of its original activity was remained after incubation at 50℃ for 1 h, and 90% of the enzym activity was observed upon storage at 8℃ for 9 days . Sugars. Na~+. Ca~(2+). and Zn~(2+) increased its activity wherease Co~(2+)and Cu~(2+) inhibited it.