Bacteria are terrific chemists, but they normally synthesize only molecules they need for their own survival, says Gallivan. His research team is interested in making bacteria synthesize molecules that they would otherwise not make on their own, resulting in molecules that may someday benefit humans. The Emory team reasoned that if a bacterium needs a particular molecule to survive, it has a strong incentive to help make it, so the goal was to make bacteria depend on a molecule that they wouldn't normally need.
In their first major breakthrough, the Emory researchers have coupled the life of a bacterium to the presence of theophylline, a compound that is used to treat asthma, and is produced by the breakdown of caffeine in both coffee and tea plants. One of the reasons that coffee has a high level of caffeine is that in the plant, caffeine is synthesized very quickly, but breaks down to theophylline very slowly.
"We know that there is an enzyme that breaks caffeine down into theophylline, but we don't know much about it," says Gallivan, an assistant professor of chemistry. "What we do know is that it works very slowly. Ideally, we would like to speed it up a bit so that we could create coffee plants that are low in caffeine. That's where the bacteria come in. They now need the breakdown product of the enzyme (theophylline) for survival, but they can't do much with caffeine."
Gallivan says that the idea is to supply these bacteria with caffeine, and give each bacterium a piece of DNA from coffee plants that may encode the enzyme that will allow
Contact: Beverly Cox Clark
Emory University Health Sciences Center