Improvement of excretory overexpression for Bacillus sp. G1 cyclodextrin glucanotransferase (CGTase) in recombinant Escherichia coli through medium optimization

Abstract

In the study presented, Design of Experiments (DOE) was combined with statistical analysis such as fractional factorial design and small central composite design Response Surface Methodology (RSM) to significantly increase the extracelullar recombinant CGTase yields in fermentation flasks. The new medium obtained by the statistical analysis for the significant medium components comprised of 12 g L-1 NZ Amine A., 24 g L-1 yeast extract, 9.44 g L-1 KH2PO4, 4.4 g L -1 K2HPO4, 4.58 mLL-1 glycerol, 7 mg L-1 sucrose and 3 mg L-1 CuCl2. Yields were improved about 68% from 9.54 to 16.07 kU mL-1 in flasks when using the optimized cultivation medium. The results suggest that the overexpression level of recombinant CGTase excreted into the culture medium using the recombinant Escherichia coli could be improved through medium optimization. © 2009 Asian Network for Scientific Information.