• Microbiology and Biotechnology Letters
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• v.17 no.4
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• pp.283-288
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• 1989

To reduce the size of 5.0kb HindIII fragment containing $\beta$-xylosidase gene, the 5.0kb insert of pAX278 which was previously cloned was reduced by various deletions and thus 1.4kb EcoRI-Xbal fragment was subcloned into pUC19, and the recombinant plasmid was named pAK208. The $\beta$-xylosidase acnivity of E. coli harboring pAK208 was higher about 1.3times than that of pAX278. For the improvement of $\beta$-xylosidase activity, we cloned and expressed the $\beta$-xylosidase gene in E. coli using vector pKK223-3 containing a potent tac-promoter, and enzyme activity of the transformant harboring pKHR212 was increased about 3.3 and 1.8 times than that of E. coli(pAX278) and Bacillus sp. K-17, respectively. To obtain better expression of $\beta$-xylosidase gene, the whole 5.0kb HineIII fragment was recloned into pC194, and the Bacillus sp. K-17 transformant harbor-ing the recombinant plasmid pCX174 showed higher activity than that of the E. coli (pAX278) and Bacillus sp. K-17, respectively. The characteristics of enzyme purified from transformants were consistent with those front alkalophilic Bacillus sp, K-17.