Phage biocontrol: how phages improve food safety
An approach called "phage biocontrol" involves the use of lytic bacteriophages to treat both food raw materials and finished products, as well as surfaces that come into contact with them, to destroy pathogenic bacteria. Phage biocontrol is gaining popularity in the US and Europe due to its effectiveness, relatively low cost, environmental friendliness, and consumer acceptance. A review of the current state of phage biocontrol is published in the journal Current Issues in Molecular Biology and is now available online .
Food poisoning is a huge global problem, both medically and economically. Physical methods of antimicrobial food treatment—heat, high pressure, and radiation—are not universally effective, while chemical methods negatively impact beneficial microorganisms and the environment. Furthermore, outbreaks of food poisoning still occur despite the use of these methods.
Bacteriophages, which are natural enemies of bacteria, act specifically, attacking only one bacterial species or strain. This allows them to destroy only the pathogenic target bacteria, leaving the normal microflora of the food product unaffected and preserving its nutritional value.
Phages are natural agents, abundant wherever bacteria are present—in soil, water bodies, the microbiota of macroorganisms, etc.—which means phage biocontrol is the most environmentally friendly of the currently proposed food disinfection methods. Experts estimate that even the widespread use of phages at maximum permitted concentrations in meat and poultry production can only increase phage numbers in the environment by millionths of a percent.
Phages can be used for the prevention and eradication of pathogenic bacteria in live farm animals, both dairy and beef. Phage preparations can be added to the animals' feed throughout their life, or applied to their skin or feathers before slaughter.
Most phage preparations approved for use in the food industry do not contain any additives or preservatives and therefore meet the requirements for the production of so-called organic products.
In terms of cost, phage biocontrol is currently almost an order of magnitude cheaper than physical treatment methods (1-4 cents/lb of product versus 10-30 cents/lb of product) and is comparable in price to the use of harsh chemical sanitizers.
Read also: Bacteriophages can protect piglets from severe infection
Of course, the high specificity of bacteriophages poses certain limitations to their use: as a rule, effective pathogen destruction is achieved by phage cocktails containing several phages specific to the main pathogens. Furthermore, phages are susceptible to chemical disinfectants and require refrigeration. The pros and cons of phage biocontrol are summarized in the table.
Table: Advantages and disadvantages of phage biocontrol
Advantages | Flaws |
Phages are of natural origin | Not all phages can be used for biocontrol. The advantages mentioned apply only to wild-type lytic phage strains. |
Phages are specific and infect only pathogenic target bacteria. | Does not provide complete eradication of pathogens if products are contaminated with species that are not targets of these phages |
Phages effectively destroy target bacteria | The narrow range of targets limits the capabilities of phages, but the solution to this problem is the use of phage cocktails |
Phages can be used only once. | No residual phage activity was observed on food products. |
The risk of bacterial resistance to phages is minimal, and there is no risk of cross-resistance to antibiotics. | Bacteria can still develop resistance to phages, but the use of phage cocktails reduces this risk. |
New phages with the desired specificity can be found relatively quickly, and their preparations are relatively easy to manufacture. | |
Phage preparations are low-toxic and do not have a negative impact on the environment. | |
Phages do not affect the organoleptic, nutritional and rheological properties of food products |
In the United States, the first phage preparation for use in the food industry was approved by the Food and Drug Administration (FDA) in 2006. Since then, the FDA has approved 13 more preparations, and several more are currently undergoing trials. Approved preparations include preparations against foodborne pathogens such as Listeria monocytogenes , toxigenic strains of Escherichia coli (particularly E. coli O157:H7), Salmonella spp., and Shigella spp.
Read more about the development of phage preparations for biocontrol here:
* Vikram A, Woolston J and Sulakvelidze A. Phage Biocontrol Applications in Food Production and Processing. Curr. Issues Mol. Biol., 2021, 40: 267-302. https://doi.org/10.21775/cimb.040.267