Methyl α-D-glucopyranoside enhances the enzymatic activity of recombinant β-galactosidase inclusion bodies in the araBAD promoter system of Escherichia coli

Abstract

In this study, we utilized a catabolite repressor to improve the enzymatic activity of recombinant β-galactosidase inclusion bodies (IBs) produced in Escherichia coli under the araBAD promoter system. Specifically, we employed methyl α-D-glucopyranoside (α-MG) to lower the transcription rate of the β-galactosidase structural gene. In deepwell microtiter plate and lab-scale fermentor culture systems, we demonstrated that the addition of α-MG after induction improved the specific β-galactosidase production, even though β-galactosidase was still produced as an IB. Particularly, the addition of 0.0025% α-MG led to the most significant increase in the specific activity of the β-galactosidase. Interestingly, the β-galactosidase IBs obtained in the presence of 0.0025% α-MG were more loosely packed, as determined by IB solubilization in guanidine hydrochloride solution. We propose that the reduced gene transcription rate was responsible for the increased specific β-galactosidase activity and the loose packing that characterized the IBs produced in the presence of α-MG. This principle could be applied throughout the enzyme bioprocessing industry in order to enhance the activity of aggregate-prone enzymes within IBs. © 2008 Society for Industrial Microbiology.