The feat, accomplished in a biology lab within the Department of Electrical Engineering, represents an important proof-of-principle in an emerging field known as "synthetic biology," which aims to harness living cells as workhorses that detect hazards, build structures or repair tissues and organs within the body.
"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," said Ron Weiss, an assistant professor of electrical engineering and molecular biology.
Collaborating with researchers at the California Institute of Technology, Weiss and graduate student Subhayu Basu programmed E. coli bacteria to emit red or green fluorescent light in response to a signal emitted from another set of E. coli. In one experiment, the cells glowed green when they sensed a higher concentration of the signal chemical and red when they sensed a lower concentration. In a Petri dish, they formed a bull's-eye pattern -- a green circle inside a red one -- surrounding the sender cells.
In addition to demonstrating that the genetic programming techniques work, this sensing system could be useful for the detection of chemicals or organisms in laboratory tests. "The bull's-eye could tell you: This is where the anthrax is," said Weiss.
The researchers published their results in the April 28 issue of Nature. In addition to Weiss and Basu, authors of the paper are postdoctoral researcher Yoram Gerchman at Princeton and professor of chemical engineering Frances Arnold and graduate student Cynthia Collins at Caltech. It was funded by a grant from the U.S. Defense Advanced Research Projects Agency.