Food scientists from Cornell University can now detect traces of E.coli in drinking water using a genetically engineered virus called a bacteriophage — a development that shows promise particularly for remote regions of the world.

Instead of dispatching water samples to a lab and subsequently waiting what could be days for the results, the team of scientists demonstrated that tests could be administered locally, with results in a matter of hours.

"Drinking water contaminated with E. coli is a major public health concern," said Sam Nugen, Ph.D., Cornell associate professor of food science. "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."

The bacteriophage, called T7NLC, bears a gene for an enzyme called NLuc luciferase — akin to the protein giving fireflies radiance. The luciferase merges with a carbohydrate (sugar) binder, so when the bacteriophage locates E. coli in drinking water, it prompts an infection that results in the creation of a fusion enzyme. Once discharged, the enzyme clings to cellulose fibers and starts to luminesce.

After binding to the E. coli, the bacteriophage impregnates the bacteria with its DNA. "That is the beginning of the end for the E. coli," said Nugen. The bacteriophage then destroys the bacterium, discharging the enzyme as well as other phages to attack remaining E. coli.

Nugen added: "This bacteriophage detects an indicator. If the test determines the presence of E. coli, then you should not be drinking the water, because it indicates possible fecal contamination."

Helping to further develop the bacteriophage is first author and Cornell doctoral candidate in food science, Troy Hinkley.

Detailing the significance of phage-based location technology, Hinkley said, "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."

The research is published in the journal The Royal Society of Chemistry.

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