Biopixels: A Psychedelic Way to Detect Heavy Metal Pollutants

Researchers at UC San Diego have built a bacterial light source of about 13,000 "biopixels," as they call it. Their work on synchronized fluorescent protein expression was published in Nature last week. This is not only a new form of art but also a piece of high-tech bioengineering. The light-producing chips consist of more than 50 million bacteria that interact and synchronize with each other using a mechanism known as quorum sensing, a method in which bacteria communicate with their fellows and gives them group-like behavior. They can regulate gene expression according to the density of the population or to determine adaptation strategies to their local environment.

The researchers in San Diego coupled the expression of a fluorescent protein to a biological clock which is synchronized with other colonies using a quorum-sensing mechanism. In this way the bacteria will periodically fluoresce in unison like blinking light bulbs.

Besides being a biological psychedelic groove light, this technique can be used for useful applications. For example, researchers can create the group-engineered bacterial sensor capable of detecting low levels of arsenic in which decreases in the frequency of the oscillations of the cells' blinking pattern indicate the presence and correlate with the amount of the arsenic poison. They foresee that this approach can be used to detect heavy metal pollutants and disease-causing organisms in a low cost array.

Jeff Hasty, 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, commented:

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. 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 colonies are synchronized via the gas signal, but the cells are synchronized via quorum sensing. The coupling is synergistic in the sense that the large, yet local, quorum communication is necessary to generate a large enough signal to drive the coupling via gas exchange.

Hasty said he believes that within five years, a small hand-held sensor could be developed that would take readings of the oscillations from the bacteria on disposable microfluidic chips to determine the presence and concentrations of various toxic substances and disease-causing organisms in the field.

This post also appears on medGadget, an Atlantic partner site.