Broad and efficient control of major foodborne pathogenic strains of Escherichia coli by mixtures of plant-produced colicins

Abstract

Enterohemorrhagic Escherichia coli (EHEC) is one of the leading causes of bacterial enteric infections worldwide, causing ∼100,000 illnesses, 3,000 hospitalizations, and 90 deaths annually in the United States alone. These illnesses have been linked to consumption of contaminated animal products and vegetables. Currently, other than thermal inactivation, there are no effective methods to eliminate pathogenic bacteria in food. Colicins are nonantibiotic antimicrobial proteins, produced by E. coli strains that kill or inhibit the growth of other E. coli strains. Several colicins are highly effective against key EHEC strains. Here we demonstrate very high levels of colicin expression (up to 3 g/kg of fresh biomass) in tobacco and edible plants (spinach and leafy beets) at costs that will allow commercialization. Among the colicins examined, plant-expressed colicin M had the broadest antimicrobial activity against EHEC and complemented the potency of other colicins. A mixture of colicin M and colicin E7 showed very high activity against all major EHEC strains, as defined by the US Department of Agriculture/Food and Drug Administration. Treatments with low (less than 10 mg colicins per L) concentrations reduced the pathogenic bacterial load in broth culture by 2 to over 6 logs depending on the strain. In experiments using meats spiked with E. coli O157:H7, colicins efficiently reduced the population of the pathogen by at least 2 logs. Plant-produced colicins could be effectively used for the broad control of pathogenic E. coli in both plant-and animal-based food products and, in the United States, colicins could be approved using the generally recognized as safe (GRAS) regulatory approval pathway.antimicrobials | colicin | EHEC | food safety | plant-made recombinant proteins

Natural plant products inhibits growth and alters the swarming motility, biofilm formation, and expression of virulence genes in enteroaggregative and enterohemorrhagic Escherichia coli

“…Thus, prevent or minimize food contamination by these bacteria are the best options to reduce health risks. Currently, thermal inactivation and using chemical preservatives are among the most effective methods for bacteria control (Schulz et al, 2015).…”

Smarter arrow now available in the food safety quiver

“…These studies demonstrated that colicins could be used to reduce populations of several species of foodborne pathogenic bacteria on food products, and in live animals (20). The present study by Schulz et al (3) indicates that plant-made recombinant protein colicins can provide relatively large amounts of a variety of colicin types active against E. coli O157:H7 for use as treatments of crops, live animals, or finished foods. This exciting result indicates that for the first time to our knowledge, colicins as specific purified proteins will finally become a viable solution to be used to reduce the foodborne pathogenic bacteria burden entering the food supply.…”

The therapeutic potential of bacteriocins as protein antibiotics

“…Recently, production of bacteriocins in plants has been achieved at costs that may encourage commercialization [80]. However, interactions between pathogenic and probiotic species in the setting of an in vivo microbiome are not yet understood well enough to predict their success [27].…”