| In this paper, author made the systematic study on the properties of Aspergillus niger SD-03producing xylanase by solid fermentation. Fistly, the solid fermentation conditions for xylanase were optimized. Optimization of the solid fermentation conditions was divided into two parts, one part was optimization of the solid fermentation conditions for xylanase using wheat bran, the other part was optimization of the solid fermentation conditions for xylanase using corn bran. Secondly, author made a preliminary study on the properties of the crude enzyme. The results are as follows:1The best fermentation conditions using wheat bran as main substrate was:the ratio of wheat bran and corn bran was7:3, add10%of straw,0.2%CaCl2,20ml water, natural pH, cultured84hour for30℃. on this condition, enzyme activity reached2183.77U/g, increasing about four times than the former.2The best fermentation conditions using corn bran as main substrate was:9g corn husk,1g bran, the size of corn bran particles is0.5mm-1mm,3.5ml A salt,0.035ml B salt,21.5ml water,0.8%glucose, natural pH, cultured132hour for28℃, and ultimately enzyme activity reached2688.06U/g, increasing five times more than the former.3The study on the properties of the crude enzyme demonstrated, the enzyme’s optimum reaction temperature was50℃, the optimum pH was6. The enzyme was stable when the temperature was range of30℃-40℃, enzyme activity mostly lose when the temperature reached60℃and preserve heat for thirty minutes. pH stability of the enzyme was relatively high, enzyme was stable when pH was range of2-10, enzyme activity began to reduce only when the pH reached above10. Zn2+, Mg2+could promote activity of the enzyme. Hg2+,Fe3+,Cu2+had great inhibition on the enzyme, and inhibition of Hg2+was most obvious, high concentrations of Hg2+almost deactivated the enzyme.The other ions showed insignificant effects on the activity of the enzyme, most of them made activity of the enzyme reduce slightly. |
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