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Year: 2011  |  Volume: 10  |  Issue: 2  |  Page No.: 209 - 214

Effect of Signal Sequence on the β-xylanase from Thermomyces lanuginosus SKR Expression in Escherichia coli

K. Khucharoenphaisan and K. Sinma    

Abstract: Xylanase is useful enzyme in various industrial such as conversion of lignocellulose to fermentable sugars for the production of chemicals and biofuels. Thermomyces lanuginosus is a potent thermophilic strain which produces high level of cellulose-free xylanase. The aim of this study was to investigate the effects of signal sequence on T. lanuginosus xylanase expression in Escherichia coli. The xylanase gene from those was amplified with and without signal sequence and expressed in E. coli. The result showed that the transformant (pUC/Xynsig) containing original signal sequence from T. lanuginosus SKR produced xylanase with 56% higher than that of another transformant (pUC/Xyn) lacking of original signal sequence. The recombinant enzymes were partially purified using ammonium sulfate precipitation and DEAE cellulose column and then determined some properties. The optimal pH and optimal temperature of xylanase from pUC/Xynsig was pH 6.0 and 50°C, respectively. In case of pUC/Xyn without signal sequence, the values of xylanase showed higher than those having pH 7.0 and temperature of 70°C in which was similar to original host. In conclusion, original signal sequence from T. lanuginosus SKR could increase xylanase production when expressed in E. coli but some properties of expressed enzyme were changed. However, this finding could apply to other expression system of various hosts in order to stimulate the level of the protein production.

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