Studies On The Production Processes And Enzymatic Property Of Axylanase With Aspergillus Niger

In this thesis, the author investigated the influence factors on thexylanase generation of Aspergillus niger 205 screened, and its enzymaticproperty as well.Based on sigle factor and experiments design of quadraticorthogonality regression method, the optimal compositions offermentation medium were as follows(%):corncob 4, peptone 0.6, beefextract 0.4, NaNO₃ 0.3, KH₂PO₄ 0.5, K₂HPO₄ 0.7, MgSO₄·7H₂O 0.06,ZnSO₄ 0.002g, COCl₂ 0.003g, xylan 0.05, bagasse 0.1 (evocator).Theoptimal size of corncob was 250 mesh. Co²⁺,Na⁺ and Mg²⁺had activationeffect to the production of Aspergillus niger 205, while Fe²⁺,Mn²⁺ andCa²⁺ had relatively strong inhibition effect.The optimal culture conditions were as follow: The initial pH of medium 4.67(natural pH),fermentation temperature 40℃,inoculum size12%,fermentation time 72h. The experiment also studied the influenceof dissolved oxygen to Aspergillus niger 205 produces xylanse andconcluded the optimal conditions: revolutions 180rpm, 40ml medium in250ml shaken flask, added beading (simulate agitate) go against producexylanase.The activity of xylanase could reach 35.7 u/mL, 28.7% higherthan before.Enzymatic properties experiment showed that the optimal reactionpH of xylanase was 4.4, and the xylanase was stable between pH 4～6.Soxylanase was suitable to be added to feed.The optimal reactiontemperature was 50℃and 40～50℃was good to reaction.Enzyme wasstable in 60℃. Mg²⁺,Ca²⁺ and K⁺ had activation effect to the reaction,while Zn²⁺,Cu²⁺ and Mn²⁺ had some extent inhibition effect and Mn²⁺was strong.