Bioengineers create living 'neon signs' from bacteria.

Using the same technique they used to create these flashing signs, the team also created a simple bacterial sensor capable of detecting arsenic. This sensor would make the cells blink on and off more slowly, indicating the presence of the poison, arsenic is letal to many of the cells we know nowadays (except for this unique ones).

Biologists and bioengineers at the University of California San Diego have teamed up to create living neon 

signs made up of millions of bacterial cells that fluoresce in unison like light bulbs.

In order to create the light they needed to attach a fluorescent protein to the biological clocks of bacteria and then synchronise the body clocks of the bacteria within the colony so that they glowed on and off in unison. The team created signs that spelled out "UC SD".

The team believes that because bacteria are so sensitive to any environmental pollutants, the approach could be used to design low cost biosensors that could respond to changes in the quantities of toxins over time.


Jeff Hasty, a professor of biology and bioengineering at UC San Diego, said: "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."

This paper is the latest in a series that have been published in Nature over four years. In the first paper, the team demonstrated that they could build a tunable biological clock to produce flashing bacteria. The second paper, published in 2010, showed how the team could design a network based on a communication mechanism -- known as quorum sensing -- used by bacteria that allowed them to synchronise their behaviour.

Quorum sensing is when bacteria pass small molecules between them to trigger certain behaviours. However, quorum sensing can't be used on a large scale because it takes too long for the molecules to pass across a large colony. However, the team discovered that each of the colonies emit gases that, when shared among the thousands of other colonies within a specially designed microfluidic chip, can synchronise all of the bacteria in the chip.

Hasty explained: "The colonies are synchronised via the gas signal, but the cells are synchronised 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."

The microfluidic chips -- about the same size of a paper clip and containing 50-60 million bacterial cells -- were designed by grad students Arthur Prindle, Philip Samayoa and Ivan Razinkov. Smaller chips with only 2.5 million cells were also designed.

Each of the blinking colonies form what the researchers refer to as a "biopixel", an individual point of light like a pixel on a computer monitor. The larger chips have around 13,000 biopixels, while the smaller ones have around 500.

Hasty believes that within five years the team could develop a small hand-held sensor that could take readings of the blinking of bacteria on disposable chips to check the presence and concentrations of toxic substances.

This woman: Bonnie Bassler shows us some interesting researchments on the field.



You can find the full study in Nature here.

The pathway I have used is my biology teachers blog biology to.

For the record ¡Happy New year!