Bacteriophages
What are bacteriophages and are they allowed for use in organic food production?
By Taryn Kennedy
Bacteriophages are viruses. Viruses are considered the most primitive form of life; they cannot reproduce without another organism. Once inside a cell, a virus replicates itself, kills the host cell, and thousands of virus particles spread to other cells. Bacteriophages are viruses that specifically infect bacteria, killing those bacteria in order to reproduce. When a single bacteriophage particle attacks a single bacterium, the bacterial cell bursts after a short period of time, liberating hundreds of new phage particles. The cycle continues and bacterial populations are reduced. Bacteriophages are stable in many environments. They can be isolated from soil and water, sewage and feces, farm and processing plant effluents, and foods.
Bacteriophages were first described around 1915 by F.W. Twort and F. d’Herelle. Likely the first published use of biological control, F. d’Herelle employed bacteriophages for treatment of dysentery caused by Bacillus shigella. Since their discovery as biocontrol agents, phages have been used to treat a variety of human and animal diseases.
A bacteriophage can be employed as the active ingredient in antimicrobial products. In food production, bacteriophages are utilized as an antimicrobial to control bacteria during the production of foods on the farm, on perishable foods post-harvest, and during food processing and handling. Bacteriophages offer numerous advantages as biocontrol agents against food borne pathogens. A bacteriophage will only attack its host bacteria; therefore the development of phage products is highly specific to the food pathogen of concern. Bacteriophages have been applied to control the growth of pathogens such as Listeria monocytogenes, Salmonella spp., Escherichia coli, and Campylobacter jejuni in refrigerated foods such as fruit, dairy products, poultry, and red meats.
Bacteriophage products are typically sprayed directly on food products such as fish, shellfish, and poultry prior to packaging. Fresh and processed fruits and vegetables can also be treated with bacteriophages. Many bacteriophages are generally recognized as safe (GRAS) by the FDA. Listeria-specific bacteriophages are permitted for use in food additives applied directly to food (21 CFR Part 172.785). Liquid chemical sterilants that are used solely in processed foods are regulated by the FDA, and are not considered pesticides by the EPA (40 CFR 152.6(a)). However, because the USDA classifies them as processing aids, they do not have to appear on the label when used as an ingredient within a formulated product (21 CFR 101.100(a)(3)).
A number of bacteriophages have been approved for use in organic processing and handling. Any food grade bacteria, fungi, and other microorganisms, such as bacteriophages, are allowed for use without restrictions in processing & handling as described in the NOP Rule at §205.605(a). Products that utilize bacteriophages as the active ingredient are allowed for use as sanitizers as long as they are nonsynthetic and not genetically modified (§205.105(c) & (e)). Once isolated from natural sources, microorganisms are propagated via naturally occurring biological processes such as fermentation. Bacteriophage products approved by OMRI must have compliant growth media or sufficient growth media removal steps (centrifugation, filtration, consumption, etc.). All products approved for use in organic food processing and handling must also have compliant carriers, additives, or other ancillary ingredients.
This article was originally published in the Spring 2014 edition of the OMRI Materials Review newsletter.
