this approach to more than 2 strains? How do they address issues related to requiring multiple media?
Autonomous regulation of the strain composition using orthogonal autoinducer AI-2, AI-1 and cell signaling mechanisms of bacterial quorum sensing.
The universal QS signal, AI-2, which is recognized and produced by many species of bacteria broadly indicates cell population density. This system works by rewiring bacterial QS systems so that the growth rate of communicating consortia members is controlled by interspecies signaling
The synthetic co-culture consists of an E. coli translator strain that senses AI-2 in the environment and translates this into an orthogonal QS signal (AI-1). This translator strain output, in turn, mediates the growth rate of the second strain.A second engineered E. coli controller strain has signal-mediated tunable growth rate, regulated by the level of the species-specific autoinducer signal, AI-1.
AI-1 binds LasR (constitutively expressed) and activates the las promoter resulting in expression of HPr which increases cell growth rate.
AI-1 binds LasR (constitutively expressed) and activates the las promoter resulting in expression of HPr (a phosphotransferasesystem (PTS) protein, important for sugar/glucose transport in bacteria) which increases cell growth rate.
Intestine on a chip complex culture of human gut microbiome. Jalili-Firoozinezhad, S. et al. A complex human gut microbiome cultured in an anaerobic intestine-on-a-chip. Nat. Biomed. Eng. 3, 520–531 (2019).
Controlled engineering of strains by having orthogonal AI-I receptor signals or creating a cascade of microbial growth circuits for
AI-2-dependent effects within the gut microbiota A. Approximately equal ratios of the 2 major phyla, the Bacteroidetes and Firmicutes, were found in the gut microbiota of untreated mice (left panel). Though streptomycin caused a depletion of the Firmicutes and enabled the Bacteroidetes to dominate the microbiota (middle panel), colonisation by AI-2-accumulating ΔlsrK mutant E. coli promoted an increase in abundance of the Firmicutes (right panel). B. In vitro and in vivo studies show that AI-2 regulates multiple phenotypes in different bacteria which might promote colonisation if also induced in the Firmicutes. AI-2 induces motility which could help bacteria find nutrients under conditions of starvation