Decontaminating food spray uses viruses to eliminate bacteria

Developed by researchers at McMaster University, the spray makes use of bacteriophages – harmless viruses that eat bacteria – which link together and form microscopic beads.

Those beads can then be applied to food and other materials to rid them of harmful pathogens such as E. coli 0157. Each bead is about 20 microns, (one 50th of a millimetre) in diameter and is loaded with millions of phages.

“When we spray it on food, we basically gather billions of mini-soldiers to protect our food from bacterial contamination,” said researcher Shadman Khan.

“They link together like microscopic Lego pieces. This organised natural structure makes them much more durable and easier to package, store and use.”

Before the introduction of penicillin in the 1940s, research into phage disinfectants and therapies had been very promising, but interest in developing their potential dimmed once antibiotics made from penicillin came onto the market. With antimicrobial resistance now sapping the power of existing antibiotics, there is intense new interest in phage research.

When phages – which occur naturally in the body and in the environment – contact target bacteria, they multiply, explosively increasing their antimicrobial power as they work.

“It’s a chain reaction, creating a dynamic and ongoing response that is even more overpowering than antibiotics,” said Professor Tohid Didar. “No other antibacterial product – not even bleach – has the special properties that phages do.”

Another major advantage of using phages in agriculture and food production is that they can be directed very specifically to take out harmful strains of bacteria without killing beneficial bacteria that enhance foods’ taste, smell and texture.

The researchers believe the spray has promising potential for commercial application, especially since phages have already earned approval from the US Food and Drug Administration for use in food.

It has already been shown to eliminate E. coli 0157 in lettuce and meat, which are often the sources of disease outbreaks.

The researchers believe the same approach can readily be used against other bacteria that cause food poisoning, such as Salmonella and Listeria – individually or in combination.

Phage sprays could be used in food processing, packaging and cleaning, and even as a treatment for irrigation water and equipment, stopping contamination at the source.

The group next plans to test the new material’s promising applications in medicine, where it might be used in disinfecting wounds, for example. Medical applications will take more time to be proved safe and effective, but a product made for disinfection in food processing could make it to market much more quickly.