| According to the request of practical applications, the article studied the immobilization technique which aimed to overcome the key technical problems during the industrial production of xylooligosaccharides using immobilized xylanase. The best carriers were selected from thirty kinds of carriers. The conditions for immobilization were optimized. The immobilized enzymes were systematically characterized in terms of their catalytic activity, kinetic parameters, thermal stability and application, etc. The xylooligosaccharides were produced from the hydrolysis of both dilute-alkali-treated corncob and steam-exploded corncob liquor with immobilized enzymes. The optimal hydrolysis conditions for both substrates were investigated. Results show that:1.Among the thirty kinds carriers studied, four carriers showed relatively good immobilizations effect on the xylanase from Streptomyces olivaceoviridis E-86, namely Eudragit S-10(h Eupergit C and macroporous polystyrene resin D380.2.This is the first report on the method of immobilizing enzyme using reversibility soluble-insoluble polymer in our country. The polymer showed a good immobilizing effect on the xylanase from Streptomyces olivaceoviridis E-86. The immobilized xylanase retained 91.84% of its activity upon immobilization by 1% Eudragit S-100. The activity of the immobilized enzyme reached to 74.68 U/ml, which was highest in our country.3.This is also the first report on xylanase immobilization using oxirane-group carrier. When 232 U of freee xylanase was immobilized using of 1 g carrier in the presence of potassium phosphate buffer (1M, pH 5.8) for 36~48 hours, the recovery and immobilized xylanase activity were 35% and 82 U/g, respectively4,Compared to the free enzyme, the optimum pH of immobilized xylanase from the Streptomyces olivaceoviridis E-86 shifted from 5.8 to 6.3, and was stable at pH 4~10. The optimum temperature of the immobilized enzyme increased from 60℃ to 65℃. The thermalstability of the immobilized enzyme increased significantly and its half life enhanced for more than 50%. Immobilization of xylanase with Eudragit S-100 conserved the affinity of the enzyme towards its substrate. The Km values for birch xylan, beech xylan and oat xylan slightly increased from 1.54> 1.42 and 1.15 mg ml-1 to 2.34,2.07 and 1.36 mg ml'1, respectively. Increases in Vmax upon immobilization are generally not observed. However, Vmax values of the immobilized enzyme were 82%-161% higher than those of free xylanase in this study. All ions used in the experiments could not enhance the activity of the xylanase. However, Cu, Ag, Hg ions and NBS de-activate the enzyme completely. The immobilized enzyme demonstrated a good reusability for it was able to maintain 80% of itsactivity after four cycles of sugar production continuously.5.Agood result was observed with the hydrolysis of the 4% corncob using 150 U/g of immobilized enzyme for 8 hours. The yield of Xylose, xylobiose, xylotriose and xylotetrose reached 11.0%, 45.7%, 32.5% and 10.8% respectively. The yield of xylooligosaccharide was about 89% of the total sugar. The hydrolysis rates calculated as total sugar were about 72% for the corncob xylan and 33.5% for the raw corncob. The is the highest hydrolysis level was reached for the production of xylooligosaccharidesutilizing enzymtic method present. Furthermore, this is also the first report world wide on the hydrolysis of dilute-alkali-corncob using the immobilized enzyme.6.1mmobilization of xylanase from Streptomyces olivaceoviridis E-86 on Eupergit C showed that: the optimum pH, pH stability and optimum temperature did not change significantly by the immobilization. However, its thermalstability and the stability towards metal ion were enhanced significantly. The hydrolysis rate was higher than 52% in condition where steam-exploded corncob liquor went through immobilized enzyme packed-bed reactor with a substrate space velocity 1.5 h-1. 93% of the activity retained after continuously peroration for ten days . The halflife of the immobi...
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