Solid-state fermentation conditions of acidic xylanase and its crude properties

The single-factor tests and orthogonal experiment were employed to evaluate the optimal fermentation conditions of xylanase produced by Aspergillus niger XZ-3S in this paper.The optimum fermentation conditions were as follows: the ratio of wheat bran:cob in medium 5∶3,the inoculum 1.0%,the ratio of solid to fluid 1∶1.7,the initial pH value 7.5,the temperature 28℃,and the time for fermentation 65h.Under those conditions,the enzyme activity of xylanase produced by the strain reached 23612.38IU/g dry medium.The optimal temperature and pH for xylanase for xylanase reaction were 50℃ and 5.0 respectively.The enzyme showed a high stability at pH value 3.0~8.0 below 50℃.