TECH SPECIAL..BUGS LIGHT UP

Living neon signs made of bacteria

WHEN LIFE IMITATES ART

‘Light’ created by attaching glowing protein to bacteria, colonies are then persuaded to blink in unison

Bioengineers at UC San Diego have created a living neon sign composed of millions of bacterial cells that periodically fluoresce in unison like blinking light bulbs.
Their achievement, detailed in this week’s issue of the journal Nature, involved attaching a fluorescent protein to the biological clocks of the bacteria, synchronizing the clocks of the thousands of bacteria within a colony, then synchronizing thousands of the blinking bacterial colonies to glow on and off in unison.
Using the same method to create the flashing signs, the researchers engineered a simple bacterial sensor capable of detecting low levels of arsenic. In this biological sensor, decreases in the frequency of the oscillations of the cells’ blinking pattern indicate the presence and amount of the arsenic poison.
Because bacteria are sensitive to many kinds of environmental pollutants and organisms, the scientists believe this approach could be also used to design low cost bacterial biosensors capable of detecting an array of heavy metal pollutants and disease-causing organisms. And because the sensor is composed of living organisms, it can respond to changes in the presence or amount of the toxins over time unlike many chemical sensors.
“Many bacteria species are known to communicate by a mechanism known as quorum sensing, that is, relaying between them small molecules to trigger and coordinate various behaviors,” said Jeff Hasty, a professor of biology and bioengineering at UC San Diego who headed the research. But the researchers found the same method couldn’t be used to instantaneously synchronize millions of bacteria from thousands of colonies.
“If you have a bunch of cells oscillating, the signal propagation time is too long to instantaneously synchronize 60 million other cells via quorum sensing,” said Hasty. But the scientists discovered that each of the colonies emit gases that, when shared among the thousands of other colonies within a specially designed microfluidic chip, can synchronize all of the millions of bacteria in the chip.
Each of the blinking bacterial colonies comprise what the researchers call a “biopixel,” an individual point of light much like the pixels on a computer monitor or TV screen. Agencies MM 4JAN12