Colorimetric monitoring of the activity of recombinant Escherichia coli expressing styrene monooxygenase

Biocatalysis using recombinant Escherichia coli expressing styrene monooxygenase (SMO) activity is recognized as a promising process for the production of enantiopure aryl epoxides such as (S)-styrene oxide. Generally the activity of the whole cell biocatalyst is determined by measuring the conversion of styrene into (S)-styrene oxide by gas chromatography, which is however improper for the high-throughput analysis of many samples. Here we present that styrene monooxygenase catalyzed conversion of indole into indigo can be employed to monitor the activity of recombinant E. coli expressing styrene monooxygenase. We first confirmed that the colorimetric method was effective to monitor the whole cell activity of SMO by comparing the E. coli expressing styAB with that expressing only styB in a solid culture system. Next we used the monitoring method to investigate the effect of chaperone coexpression on the SMO whole cell activity in a liquid culture system.