Bacteria have been programmed to behave like computers, assembling themselves into complex shapes based on instructions stuffed into their genes. The research could lead to smart biological devices that could detect hazardous substances or bioterrorism chemicals, scientists say. Eventually, the process might be used to direct the construction of useful devices or the growth of new tissue, perhaps restoring function to a severed spinal cord. Many lines of research hold similar promise for controlling biology to build useful things. Predictions do not always come true. What's new about this latest effort is that the bacteria are made to communicate, so that millions or even billions of them gather in a predictable manner. And there are pictures to prove it. The researchers programmed E. coli bacteria to emit red or green fluorescent light in response to a signal emitted from another set of E. coli. The living cells were commanded to make a bull's-eye pattern, for example, around central cells based on communication between the bacteria. [Live Science via Btang Phlog]