Bacteria becomes living computer

In a step toward making living cells function as if they were tiny computers, engineers at

have programmed bacteria to communicate with each other and produce colour-coded patterns.

The feat, accomplished in a biology lab within the Department of Electrical Engineering, represents an important proof-of-principle in the emerging field of 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 of 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.