Methyl alpha-D-glucopyranoside enhances the enzymatic activity of recombinant beta-galactosidase inclusion bodies in the araBAD promoter system of Escherichia coli.

In this study, we utilized a catabolite repressor to improve the enzymatic activity of recombinant beta-galactosidase inclusion bodies (IBs) produced in Escherichia coli under the araBAD promoter system. Specifically, we employed methyl alpha-D: -glucopyranoside (alpha-MG) to lower the transcription rate of the beta-galactosidase structural gene. In deepwell microtiter plate and lab-scale fermentor culture systems, we demonstrated that the addition of alpha-MG after induction improved the specific beta-galactosidase production, even though beta-galactosidase was still produced as an IB. Particularly, the addition of 0.0025% alpha-MG led to the most significant increase in the specific activity of the beta-galactosidase. Interestingly, the beta-galactosidase IBs obtained in the presence of 0.0025% alpha-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 beta-galactosidase activity and the loose packing that characterized the IBs produced in the presence of alpha-MG. This principle could be applied throughout the enzyme bioprocessing industry in order to enhance the activity of aggregate-prone enzymes within IBs.