Bacterial Sensors
Engineered E. coli bacteria signal environmental changes

Results: Princeton University and Caltech researchers have genetically engineered E. coli bacteria to give off red or green fluorescent light in response to different concentrations of a cell-signaling molecule secreted by a third type of E. coli. Incubating the three types of E. coli in petri dishes resulted in controllable patterns. In one experiment, the researchers produced concentric circles of different colors, with the signaling cells in the center. Surrounding them were two types of fluorescing cells: one that emitted green light when sensing a high concentration of the signaling molecule, and another that gave off red light at medium concentrations.

Why it Matters: Researchers had previously programmed cells to communicate individually or in small groups. Here the Princeton and Caltech team engineered larger populations of bacteria to work together to form visible patterns that could be used, for example, to signal the presence of a toxic chemical. Because the bacteria produce different signals in response to concentrations of a target chemical, they could flag areas of high concentration as likely sources of wider contamination. In theory, bacteria-based sensors could be more sensitive to a broader range of chemicals than conventional sensors are.