With some creative genetic engineering, chemists have designed bacteria that rely on a breakdown product of caffeine for their survival. The advance could eventually lead to decaffeinated coffee plants, the researchers suggest.
"The idea is to convince these microorganisms to do the chemistry that we want them to do," says Justin Gallivan, a chemist at Emory University in Atlanta. He and Shawn Desai, also of Emory, provided bacteria with a molecular switch that senses the presence of theophylline—the caffeine by-product. In response, the switch activates a gene that renders the microbes resistant to an antibiotic.
The genetic control that Gallivan designed is called a riboswitch, a segment of RNA that changes conformation when bound to certain small molecules and then turns genes on or off (SN: 4/10/04, p. 232: Available to subscribers at Quite a Switch). Riboswitches exist naturally in cells, where they regulate gene activity in response