Metabolic engineering seeks to reprogram microbial cells to efficiently and sustainably convert biomass to value-added compounds. Since chemical production can sometimes be at odds with the cell’s natural objectives, strategies have been developed to balance these conflicting goals. One such strategy is dynamic regulation, which modulates gene expression to favor biomass and metabolite accumulation at low cell-densities before diverting key metabolic fluxes towards product formation. To trigger changes in gene expression in a pathway-independent manner, without the need for exogenous inducers or human supervision, researchers have coupled gene expression to quorum sensing (QS) circuits, which regulate transcription based on cell-density. While effective, studies thus far have been limited to placing an individual gene or set of genes under control of a single QS promoter. More challenging pathways may require layered dynamic regulation strategies, motivating the development of a tool capable of regulating multiple sets of genes in which the dynamics of each regulation module can be independently tuned to maximize generalizability. We have developed a QS-based regulation tool that combines components of the <i>lux</i> and <i>esa</i> QS systems to simultaneously up- and down-regulate two sets of genes. Fluorescence characterization of the circuit revealed that varying the expression level of two QS components leads to predictable changes in switching dynamics and using components from two QS systems allows for independent tuning capability. We applied the regulation tool to successfully address two challenges in the naringenin synthesis pathway - enzyme inhibition and malonyl-coA accumulation. Through this case study, we confirmed the benefit of having (1) multiple control points, (2) predictable tuning capability, and (3) independently tunable regulation modules.

Development of a quorum-sensing circuit for multiplexed metabolic flux control in engineered bacteria

2019 Spring National Meeting

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.