Study On Production Technology And The Enzymatic Property Of Xylanase Produced By Engineered Bacteria

Based on the previous work in our lab, with gene engineering E.coli as experiment material, we studied the effects of inoculation quantity, dissolved oxygen, pH, culture temperature on the cell growth and xylanase enzyme activity with the carbon source optimized culture medium. In addition, enzymatic property, degradation production and the effects of metal ions on enzyme activity.(1) The optimization conditions were inoculum size of12%(v/v), dissolved oxygen value of25%, medium pH of6.8, temperature of37℃in cell growth period, temperature of36℃in induction period after optimizing fermentation condition for xylanase production. The fermentation results showed that the xylanase enzyme activity was stably more than700U/mL and the highest value could reach790U/mL.(2) The enzymatic property of xylanase was studied in this work. The xylanase showed the maximal activity at pH6.4. The enzyme exhibited maximal activity at55℃. It remained more than90%activity at pH ranges between pH5.2and pH8.8after dealing with2hours. Besides, the xylanase remain98.5%activity under65℃after dealing with10min, remain85%activity under80℃after dealing with10min. It exhibited a good pH tolerance and thermal stability, show it has a high production value.(3) Studied the effect of metal ions on xylanase. Na+, Ca2+, K+can enhance the enzyme activity of xylanase. Mg2+, Mn2+, Fe3+, Zn2+, Cu2+can reduce the enzyme activity of xylanase. The activation and inhibition can be enhanced with increased ion concentration.(4) The degradation production resulted from xylanase were also studied in this work by TLC. The main productions from the degradation of oat spelt xylan by xylanase included xylobiose, xylotriose, xylotetraose and xylopentaose, and their content was more than90%of the total. This kind of xylanase was characterized by endoglucanase function.