Bacteria have been programmed like a computer to produce colored patterns by communicating with each other.

The bacteria, E. coli, were programmed to emit red or green fluorescent light in response to signals from other E. coli.

In one experiment, they glowed green in high concentrations of a signal chemical and red in low, forming a bull’s-eye pattern in a Petri dish.

“We are really moving beyond the ability to program individual cells to programming a large collection?millions or billions?of cells to do interesting things,” says researcher Ron Weiss of Princeton University.

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Where the anthrax is

Collaborating with researchers at the California Institute of Technology, Weiss and graduate student Subhayu Basu have shown with their sensing system that genetic programming techniques work on a larger scale.

The work is a proof-of-principle for the field of synthetic biology, which aims to put living cells to work doing such things as detecting hazards and rebuilding damaged parts of the body.

Beyond colors, Weiss is working to have cells secrete materials that build physical devices such as antennas or transmitters.

The bulls-eye system itself, however, could have practical uses detecting chemicals and organisms.

“The bull’s-eye could tell you: This is where the anthrax is,” says Weiss.

The research is reported in the journal Nature