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Journal of Biomedicine and Biotechnology
Volume 2010, Article ID 980567, 12 pages
Research Article

Constitutive High Level Expression of an Endoxylanase Gene from the Newly Isolated Bacillus subtilis AQ1 in Escherichia coli

Center for Bioindustrial Technology, Agency for Assessment and Application of Technology (BPPT), Jl MH Thamrin no. 8, Jakarta 10340, Indonesia

Received 22 February 2010; Revised 21 May 2010; Accepted 6 July 2010

Academic Editor: Daniele Daffonchio

Copyright © 2010 Is Helianti et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


A xylanolytic bacterium was isolated from the sediment of an aquarium. Based on the 16S rDNA sequence as well as morphological and biochemical properties the isolate was identified and denoted as Bacillus subtilis (B. subtilis) AQ1 strain. An endoxylanase-encoding gene along with its indigenous promoter was PCR amplified and after cloning expressed in E. coli. In E. coli the recombinant enzyme was found in the extracellular, in the cytoplasmic, and in the periplasmic fraction. The specific activity of the extracellular AQ1 recombinant endoxylanase after 24-hour fermentation was very high, namely, and  U/mg in LB and LB-xylan medium, respectively. This activity was clearly exceeding that of the native B. subtilis AQ1 endoxylanase and that of 95% homologous recombinant one from B. subtilis DB104. The result shows that the original AQ1 endoxylanase promoter and the signal peptide gave a very high constitutive extracellular expression in E. coli and hence made the production in E. coli feasible.