The Future

What Are Bacteriophages And How Do They Make Food Safer?

Bacteriophages are viruses that track down and kill bacteria. Discover how these bacteria killers can be used to make our food safer and what’s holding them back.

It only takes one small bite of undercooked chicken to trigger a biohazard in your kitchen. In the best-case scenario, food poisoning leads to a few days spent curled up in bed, but at worst, it can lead to life-threatening complications. What if we could eliminate the contaminants causing illness at their source? This is where bacteriophages come into play.

What exactly are Bacteriophages?

Bacteriophages, also known as phages, are viruses that exist in all environments, including soil, water, sewage slurries, and even the human gut microbiome.¹ They infect bacteria, including those designated as pathogens—the organisms responsible for making us sick.

Predating the development of antibiotics, the main feature that sets phages apart from other imprecise antimicrobial drugs is their high degree of specificity.² In simpler terms, phages are target killers: they infect one strain of bacterial cells at a time through an enzyme called endolysin. Then, they inject their DNA, multiply and neutralise the bacterial load by bursting their host cell’s walls.

Phages kick food safety up a notch

According to a review published in Food Science & Nutrition in March 2023, contamination with foodborne pathogens has two immediate outcomes. As well as resulting in food waste, it constitutes a major threat to public health.³ The WHO estimates there are 600 million yearly reported cases of foodborne diseases and 420.000 deaths worldwide, which are directly linked to increased hospital pressure and an overall surge in healthcare costs.⁴ These incidents highlight the importance of finding effective methods to eliminate harmful microorganisms from our food.

Researchers have been studying the application of phages in a wide range of settings, including agriculture, animal and human infections. However, at present, phages are mostly used in the US by serving as an add-on to HACCP protocols already in place during food production.

Editor’s Note: HACCP stands for Hazard Analysis Critical Control Point. It’s an internationally recognised system to make our food system safe - by looking out for and reducing risks. For example, a restaurant serving chicken to customers might use the seven-step HACCP process to make chicken safe for their clients. After identifying the risk of bacteria in undercooked chicken, the chef would decide to always make sure the chicken is cooked until 74 degrees Celsius. The chef could check the temperature with an internal thermometer and keep cooking the chicken for longer if needed. Keeping a record of these actions is also part of the HACCP process, which will provide evidence of safe food practices if the restaurant has an inspection.

Unlike many other methods to improve food safety, phages suppress bacteria without affecting the taste, texture and nutritional quality of foods. Although synthetic chemicals may be more effective at killing bacteria, these also seep indefinitely into food, whereas phages don’t linger for long without a host.⁵

Friends or foes? Room for phage-scepticism

Using new technology in our food can feel worrying for consumers. But in this case, fears seem to be misplaced. Phages are everywhere, even on some of the food we already consume, without seeming to cause any problems. After the FDA gave its first approval for using phages in meat and poultry products in 2006, companies like PhageGuard in the Netherlands have eyed the possibility of marketing phage products to prevent foodborne pathogens.⁶ The European Court of Justice only permitted the use of Listex, one FDA-approved phage solution, in food products in 2019.⁷ However, without clearer EU guidelines available, we still can’t be sure what the future is for phages in the European Region.⁸

Is animal farming the canary in the coal mine?

Among the most frequent foodborne bacteria are Campylobacter, Listeria monocytogenes, E. coli and Salmonella: these are of animal origin and carried by cattle, poultry and pigs in their bowels.⁹ The rise in global temperatures, steered by a changing climate, makes heat-stressed livestock more vulnerable to contracting illnesses. Cramped living conditions for livestock and a warming climate inevitably lead to more bacterial replication, with pathogens evolving and spreading through the food chain.¹⁰

As a response to illness rising in farm animals, we tend to use more and more antibiotics. But the overuse of antibiotics increases the risk of antibiotic resistent bacteria. These superbugs are no longer responsive to multiple antibiotics and can be transferred to humans through food or contact with animals. This unrestrained use of antibiotics in factory farming is associated with the emergence of superbugs. As well as providing better welfare and more hygienic conditions for livestock, phages could prove useful for sanitisation and as a preventative strategy on the farm. But bacteriophages do come with some limitations.

Limitations of phages in food safety:

1. Phages aren’t immune to resistance

Although phages have some potential to reduce our dependence on antibiotics, it turns out that bacteria can develop phage resistance mechanisms as well, which has prompted a call for judicious use. Searching for a solution to this hurdle, researchers have been testing cocktails of phages mixed with antibiotics. In so doing, resistance mechanisms are expected to take longer to develop because the harmful agent would have to fight against multiple threats at once.¹¹

2. Phages aren’t a priority for many food producers

Since contamination can occur along all stages of the food chain (i.e., pre-harvest, post-harvest, food processing, transportation and storage), phages may extend the shelf life of food but do not entirely eradicate the chance of it going bad before we get a chance to eat it. From the viewpoint of food companies, it could be far more logical to scale up food production rather than spending more to extend the shelf life of current produce.

3. It’s hard to regulate rapidly-evolving phages

Phages outpace clinical trials by evolving rapidly. This is an issue because the veterinary medicines administered to livestock must comply with strict rules.¹² Even if experimental phage-based therapy performs well in a lab environment, it remains too unpredictable a factor when it comes to imagining an extensive rollout at the farm level.

‘Phages are biological products, not a chemical formula that can be produced again and again. After time, when we have new bacterial strains with new mechanisms of antibiotic resistance, we can update our commercial product. This is very challenging for the Good Manufacturing Practice (GMP) standards.’ Dr Mzia Kutateladze, Director of the Eliava Institute in Georgia, told Food Unfolded.¹³

Phages are definitely no silver bullet in the face of rising drug resistance. But if used carefully, they could be another helpful tool to help enhance food safety and slow down the tide of the antibiotic resistance crisis.