Communication and collaboration in synthetic microbial consortia

The development of synthetic microbial communities presents unique opportunities for carrying out complex tasks through a division of labor approach. Each organism may be optimized individually and, much like at the genetic circuit level, organisms may be used in different combinations to carry out different processes or tasks. One of the major challenges with respect to engineering increasingly complex synthetic microbial consortia is the development of new biological components that enable cell-cell communication, and enable coordinated, population level behaviors.To this end, we have developed a new set of transcriptional regulators and promoters based on the esa quorum-sensing system that can be used to turn gene expression on or off in response to a cell-cell communication signal. We have also developed a set of AND-gate promoters to demonstrate that EsaR and its target DNA sequence can be used to engineer new combinatorial promoters that respond to cell-cell communication and a second, exogenous input. To expand our ability to use mixtures of diverse microbial species, we have developed a synthetic communication pathway between a representative Gram-negative organism (Escherichia coli) and representative Gram-postitive organism (Bacillus megaterium). An acyl-homoserine lactone (AHL)-dependent system was adapted to send signals from B. megaterium to E. coli. Components of a peptide-dependent microbial signaling pathway were used to send signals from E. coli to B. megaterium. We anticipate that our communication system, when combined with strategies for fine-tuning ecological interactions, will be a key technology for the implementation of synthetic consortia for bioprocessing, metabolic engineering and other applications.