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Figure 2 | Bioresources and Bioprocessing

Figure 2

From: Programming the group behaviors of bacterial communities with synthetic cellular communication

Figure 2

Cellular density control enabled by engineered cellular communications. (A) A communication-based gene circuit that confers the auto-regulation of cellular population density. In this system, a positive correlation between cell density and AHL concentration is essential and was created by having the cells constitutively produce LuxI that catalyzes AHL synthesis. At a low density, cells survive and grow normally because the expression of the toxin gene ccdB is not activated by a low AHL level. In contrast, when cell density achieves a critical level, ccdB expression is triggered by accumulated AHL, causing cellular death. The density-dependent cell death ensures an automatic control of total population density. (B) A synthetic gene circuit conferring an Allee effect in an isogenic population. Rather than the toxin CcdB in (A), the antitoxin CcdA was correlated with cellular density via AHL concentration. At a low cell density, the cells cannot survive because of their production of the toxin CcdB. At a high density, the production of the antitoxin CcdA is triggered to neutralize the toxic effects from CcdB, resulting in normal cell growth.

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