Construction of gene engineered Escherichia coli strain for high-yield production of indigo and its stability

As the natural food blue pigment sources are comparatively rare, microbial fermentation is an efficient way to produce the natural indigo pigment.In this study, the styrene monooxygenase gene sty AB was cloned from Pseudomonas putida B3 and then over-expressed in Escherichia coli, generating the gene engineered strain E-AB for high-yield production of indigo. By fermentation conditions optimization, a maximum yield of 68.9 mg/L of indigo was obtained in E-AB using indole as the substrate, which was 5.4-fold higher than that of wild-type strain B3. The indigo stability was further investigated under different temperature and illumination conditions.High temperature and UV light obviously enhanced indigo degradation, while low temperature and light-proof condition could delay indigo degradation. And it was detected that isatin was the main degradation compound during indigo degradation.These results would provide the theoretical support and technical guidance for high efficient biotransformation preparation and application of the natural indigo pigment.