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Glowing viral: Luminescent bacteria used to detect E.coli in drinking water

Scientists have engineered a virus that can find and destroy E.coli in drinking water within hours.

Most strains of E.coli are harmless and often found in human and animal intestines, but others can have serious impacts on health. The World Health Organisation estimates E.coli is responsible for almost 63,000 deaths per year.

The new test, which was developed by food scientists from Cornell University in the US, can be administered on site. This is particularly useful as E.coli contaminated water is more prevalent in rural areas and in developing countries, where sending water samples to a lab for testing is not always possible.

In their paper, published in The Royal Society of Chemistry journal Analyst, the researchers said rapid detection of E.coli was important as many strains have low infectious doses – meaning even a small amount of contaminated water or food can make someone ill.

“Drinking water contaminated with E. coli is a major public health concern,” Cornell Associate Professor of Food Science Sam Nugen said.

“If the test determines the presence of E. coli, then you should not be drinking the water because it indicates possible fecal contamination.”

The test uses a bacteriophage – a genetically engineered virus – that carries a gene for the enzyme NLuc luciferase. This is similar to the protein that gives fireflies their glow and was based on the enzyme from a type of deep sea shrimp that secretes a blue liquid as a defense mechanism.

When the bacteriophage detects E.coli in water and starts to infect it, it triggers the production of the NLuc luciferase, which produces light. So if the engineered virus finds E.coli in a water sample, it will glow.

“These phages can detect their host bacteria in sensitive situations, which means we can provide low-cost bacteria detection assays for field use like food safety, animal health, bio-threat detection and medical diagnostics,” Nugen said.

After the bacteriophage binds to the E.coli, the phage shoots its DNA into the bacteria. Nugen said this is “the beginning of the end” for the E.coli as the phage breaks open the bacteria, releasing the enzyme as well as additional phages to attack other E.coli.

Fellow author of the study Troy Hinkley is currently working as an intern with Intellectual Ventures/Global Good, a group that focuses on philanthropic scientific research, to further develop the test.

He said it has the potential to improve the lives of people who would otherwise contract a preventable disease through drinking contaminated water.

“Phage-based detection technologies have the potential to rapidly determine if a water source is safe to drink, a result that serves to immediately improve the quality of life of those in the community through the prevention of disease,” Hinkley said.