Bioengineers and biologists from the University of California San Diego have created neon signs made from millions of bacteria that light up in unison.

The researchers engineered a single fluorescent protein to the biological clocks of bacteria. Next the team synchronized the body clocks of the bacteria in a colony so that they will glow on and off in unison. The researchers have successfully turned the neon bacteria into a sign that spells out UCSD. The largest sign the team made so far is the about the size of a paper clip but theoretically the bacteria could even spell out signs in retail or bar window.

On a practical level the blinking bacteria could be used as biosensors capable of detecting heavy metal pollutants and disease-causing organisms. Because the sensor is made from living organisms, it can detect minute changes to the amount of toxins in the human body over time unlike many chemical sensors.

"These kinds of living sensors are intriguing as they can serve to continuously monitor a given sample over long periods of time, whereas most detection kits are used for a one-time measurement," said Jeff Hasty, a professor of biology and bioengineering at UC San Diego who headed the research team in the university's Division of Biological Sciences and BioCircuits Institute. "Because the bacteria respond in different ways to different concentrations by varying the frequency of their blinking pattern, they can provide a continual update on how dangerous a toxin or pathogen is at any one time."

The team has already created a biosensor that detects levels of arsenic in metal. The bacteria were able to detect the arsenic and blinked more slowly as the amount of arsenic increased. These sensors are also cost effective as they only cost $100 to build and last for weeks at a time.

For now the team is concentrating on finding out the limit for their blinking bacteria. Hasty said the team is looking at how many cells they can use to get a macroscopic result.

The team's findings will be published online Sunday in the journal Nature.