Gene amplification and overexpression of Bacillus subtilis L-asparaginase

Background and objectives The aim of this paper was to focus on improving production level of l-asparaginase by developing recombinant strains. Materials and methods Asp gene was cloned into the shuttle vector pNW33N, and the recombinant plasmid was used to transform Bacillus subtilis protoplast. Asp gene was expressed into both Escherichia coli and B. subtilis. Enzyme activity of the recombinant strains was measured as compared with wild-type strains. Results Asp gene was successfully subcloned into the recombinant plasmid named S-ASP-NRC-27. The gene was expressed efficiently in both host strains: E. coli and B. subtilis. The enzyme activity of the transformants was increased up to threefold under control of Lac Z promoter. Conclusion From the previous results, the shuttle vector pNW33N seemed to be a very useful plasmid as a cloning vector in a wide variety of the genus Bacillus. Both of Asp gene amplification and the control of Lac Z promoter had direct effects on producing the super Asp-expression strains.