A Synchronous Clock Made of Bacteria

January 25, 2010

It's not your typical clock. Rather than a quartz movement and sweeping second hand, the heart of this device is a colony of genetically engineered bacteria. A deceptively simple circuit of genes allows the microorganisms to keep time with synchronized pulses of fluorescent light, beating with a slow, rhythmic flicker of 50 to 100 minutes.

The bacteria represent the first synchronized genetic oscillator. Scientists say the tool will be foundational for synthetic biology, an offshoot of genetic engineering that attempts to create microorganisms designed to perform useful functions. The oscillator might one day provide the basis for new biosensors tuned to detect toxins, or for cellular drug delivery systems designed to release chemicals into the body at preprogrammed intervals.

Oscillators are an integral part of the biological world, defining cycles from heartbeats to brain waves to circadian rhythms. They also provide a vital control mechanism in electronic circuits. Biologists first set out to engineer a biological version more than a decade ago, creating a circuit dubbed the 'repressilator.' (The creation of the repressilator, along with a genetic on-off switch, in 2000 is generally considered the birth of synthetic biology.) However, early oscillators lacked precision--the rhythm quickly decayed, and its frequency and amplitude couldn't be controlled.