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KMID : 0545120020120050766
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Journal of Microbiology and Biotechnology
2002 Volume.12 No. 5 p.766 ~ p.772
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Surface Immobilization on Silica of Endoxylanase Produced from Recombinant Bacillus subtilis
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KANG, SU-CHEOL
KIM, HYE-JEONG/NAM, SOO-WAN/OH, DEOK-KUN
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Abstract
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The plasmid, pJHKJ4, containing the endoxylanase gene, was introduced into Bacillus subtilis DB 401. The recombinant cells produced 587 until/ml of endoxylanase at 33 h. The endoxylanase was immobilized convalently on the surface of silica for effective xylan hydrolysis. The activities of the immobilized and free endoxylanase were optimal at pH 6.5 and 10mM MmSO_4. The optimal temperature of the immobilized endoxylanase was 60℃, whereas that of the free endoxylanase was 65℃. Under these optimal conditions, the activity of the immobilized endoxylanase was 1.7 times higher than that of the free endoxylanase. From microscope photographs, the immobilized endoxylanase was found to be bounded and evenly distributed on the surface of silica, a nonporous solid support. The enzyme kinetic between the immobilized and free endoxylanase was estimated to be uncompetitive, when plotting double-reciprocal plots against xylan concentrations and endoxylanase activities. These results suggest that the higher activity of the immobilized endoxylanase may be due to increased formation of enzyme-substrate complex, because of the easy accessibility of the immobilized enzyme to the polysaccharide-xylan as a high molecular weight substrate.
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