Synthetic interspecies communication between escherichia coli and bacillus megaterium

Abstract

Single monoclonal microorganisms have been extensively optimized for the manufacture of valuable biomolecules from pharmaceuticals to bioplastics. However, many challenges are still faced by the utilization of a single population including toxic byproduct accumulation and suboptimal nutrient allocation. Utilizing microbial consortia has the potential of carrying out complex, novel, and challenging processes by coordinating complementary metabolic pathways of two or more microorganisms. Cell-cell communication mechanisms can serve as the primary tunable synthetic tool for guiding desirable interactions between different microorganisms. However, few reliable systems for communication between Gram negative and Gram positive organisms are still needed. The goal of our work was to establish these communication platforms between a Gram positive and a Gram negative microorganism. The biotechnologically important Bacillus megaterium was engineered to produce the communication signal, acyl homoserine lactone (AHL).

We demonstrate the development of a one way synthetic communication system between an AHL B. megaterium producer and an AHL Escherichia coli receiver. This is the first time that a Gram positive microorganism is shown to produce AHL and synthetically induce gene expression from a Gram negative microorganism. To complement this one way communication, an orthogonal quorum-sensing (QS) system was implemented to send signals back from E. coli to B. megaterium. The agr QS system which utilizes auto inducing peptides (AIP) was modified and combined with the AHL signaling pathway to enable two way communication between B. megaterium and E. coli. While troubleshooting the integration of these systems in B. megaterium, we were able to generate new expression platforms in B. megaterium. We were able to design and select a two way communicating B. megaterium as well as a two way communicating E. coli. These bacteria will serve as a model for future synthetic microbial consortia as they have the potential to be expanded into related microbes as well as to be used as anchoring hubs for expanded microbial consortia.