Construction of Synthetic Microbial Consortium for Violacein Production

Violacein, a purple-colored natural pigment produced by microbes, has anti-microbial, anti-parasitic, and anti-cancer properties. Violacein can be synthesized through a complex pathway from a carbon source via tryptophan. One strategy to optimize the production of a target product with a complicated pathway is to divide the biosynthetic pathway into two or more host cells to alleviate the complexity of pathway optimization. In this study, we construct a synthetic microbial consortium consisting of two strains; one is to produce tryptophan from a carbon source, and the other is to convert tryptophan to violacein. This system enables easy fine-tuning of the violacein synthetic pathway by adjusting the ratio of two strains. To monitor the growth dynamics of two strains, we develop a fluorescence-based real-time population monitoring system. Then, we optimize the medium composition and culture condition for the synthetic microbial consortium, including carbon sources, initial inoculation ratios, induction timings, and surfactants. With the optimized condition for the consortium, we improved violacein production 2.79-fold in titer.