Bioengineers create living neon sign composed of bacteria

Bioengineers in the US have created a living neon sign composed of millions of fluorescent bacterial cells — that could lead to organic germ detectors.

A research team from the University of California San Diego used a fluorescent protein and a microfluidic system to cause thousands of colonies of bacteria to glow on and off in unison.

As well as demonstrating how researchers in the field of synthetic biology can engineer living cells like machines, the project also produced bacterial sensors, which could lead to devices for detecting pathogens and heavy-metal pollutants.

The thousands of bacteria within each colony, or ‘biopixel’, were synchronised using a network based on the organisms’ molecular communication system, which co-ordinated their biological clocks and caused them to flash at the same time.

However, to synchronise the fluorescence between biopixels, the researchers had to design a microfluidic system, to deliver gas emitted by the bacteria between the different colonies. This gas acted as a signal, telling the bacteria when to flash on and off.

The largest microfluidic chips contain a total of 50- to 60-million bacterial cells in about 13,000 biopixels and are about the size of a paper clip.

Using the same method, the researchers also built a biological sensor that can detect low levels of arsenic, indicated by decreases in the frequency of the biopixels’ blinking pattern.

‘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 research leader Prof Jeff Hasty.

‘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.’

Hasty said a small handheld sensor could be developed within five years that would use disposable microfluidic chips containing bacteria colonies to determine the presence and concentrations of various toxic substances and pathogens in the field.