Predator Virus Attacks Lethal E. coli at Source

July 16, 2008

Researchers Work with Natural Enemies of Bacteria to Deter Prevalent Pathogen on Farms and Feedlots

Researchers at The Evergreen State College in collaboration with the U.S. Department of Agriculture at Texas A&M have been working to increase food safety by reducing the populations of E. coli in the guts of sheep and cattle. The goal of the research is to increase understanding of the complex predator-prey relationship between bacteria (the prey) and bacteriophages (the viral predator). The research could lead to safer food.

E. coli O157:H7 is a dangerous bacterial food pathogen that occurs naturally in the guts of livestock without making them sick. E. coli is easily passed from farm animals to humans. The bacterium causes food poisoning, sickness, and sometimes death in people who eat tainted meat or contaminated produce or water.

Andrew Brabban and Betty Kutter, microbiologists at Evergreen State College in Olympia, Washington, have been studying tiny E. coli predators known as bacteriophages, which attack E. coli bacteria. The Evergreen State phage biology lab was established in 1973 and together Kutter and Brabban have more than six decades of research experience on phages.

Brabban, Kutter, and colleagues have uncovered bacteriophages that attack various strains of E. coli naturally in cattle or sheep’s stomach. Recent results appeared under the title “Prevalence of Escherichia coli O157 and O157:H7-infecting bacteriophages in feedlot cattle feces” in the October issue of Letters in Applied Microbiology. The research is funded by the U.S. National Institutes of Health, Phage Biotics, the National Cattlemen’s Beef Association and the U.S. Department of Agriculture.

By using phage as a natural predator, it may be possible to better target and tame E. coli and increase the safety of food. Using bacteriophages provides a potentially cheap and broadly applicable way to treat cattle that offers advantages over traditional antibiotics.

Phage treatment is more specific to E. coli, which means it is less likely to encourage resistance in other harmful bacteria and less likely to kill useful bacteria. Also, much like the bacteria, the bacteriophage is easily transferred from one infected individual to another, resulting in a more robust solution to E. coli infections.

Economic impacts could also be significant. “E. coli contamination results in waste of meat, and ultimately wasted meat costs consumers,” says Brabban. “Hundreds of millions are also spent to treat E. coli infections,” he adds.

But while economics are important, healthier food is the top priority of the research. “It would be very rewarding if we could come up with an increased understanding or an application that leads to safer food down the line,” says Brabban. “We all would like food to be safer.”