Programming Nutrient Detection with Modular Regulators for Dynamic Control of Microbial Biosynthesis

Dynamic control of biosynthetic pathways improves the bioproduction efficiency. One common approach is to use genetic sensors that control pathway expression in response to a nutrient molecule in the target feedstock. However, programming the cellular response requires the engineering of numerous genetic parts, which poses a significant barrier to explore the use of different nutrients as cellular signals. Here we created a dynamic control platform based on a set of modular transcriptional regulators; these regulators control the same promoter for driving gene expression, but each of them responds to a unique signal. We demonstrated that by replacing only the regulator, a different nutrient molecule can then be used for induction of the same genetic circuit. To show host versatility, we implemented this platform in both <i>Escherichia coli</i> and <i>Pseudomonas putida</i>. This platform was then used to program the induction of ethanol production by three nutrients, fructose, cellobiose, and galactose, of which each molecule can be present in a different set of crops. These results suggest that our platform facilitates the use of different agricultural products for the dynamic control of biosynthesis.