Battle of the Pathogens: ‘Good’ Bacteria Shown to Fight Salmonella on Tomatoes

Researchers at the U.S. Food and Drug Administration (FDA) have found powerful “good” bacteria that can fight Salmonella on the surface of tomatoes, a discovery that could be a major breakthrough in food safety science.

“Americans consume extraordinary amounts of tomatoes,” said Eric Brown, a chief microbiologist at FDA’s Center for Food Safety and Applied Nutrition, who explains that tomatoes are one of the “latest battlegrounds” for Salmonella, a leading cause of foodborne illness.

According to Brown, FDA scientists have been trying to figure out exactly why there has been an uptick in Salmonella contamination in fresh produce, and explore ecologically sound interventions for disrupting the spread of the pathogen.

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To investigate the Salmonella tomato predicament, a team of FDA scientists–‘team tomato’–has spent a lot of time over the past several months in the Eastern Shore of Virginia, where the vast majority of the state’s tomatoes are grown.

The group, led by Brown, aimed to detect a non-pathogenic, natural antagonist against Salmonella Newport and other salmonellae associated with tomatoes.

Team tomato’s research found about a dozen types of ‘good’ bacteria could inhibit or destroy Salmonella on the skin of a tomato.

Research found that that Salmonella start to bubble and disperse when good bacteria was introduced. 

“This is the wresting ring,” says Brown, as he points to a picture of the experiment–the group placed Salmonella on tomato skins inside a marker circle and then added the antagonist bacteria. 

Scientists also pitted the so-called ‘wonderbugs’ against pathogens like E. coli O157:H7 and Listeria monocytogenes in lab experiments. According to Brown, harmful pathogen growth was “extremely retarded” when the good bacteria was introduced in each case.

Scientists say more research is needed, but the new science looks promising for agricultural application. It is still early to say how exactly the good bacteria could be used in a food safety system, but it is possible that it could be turned into a crop spray used before harvest.


Brown and his tomato team see preventing Salmonella contamination as critical, especially given the difficulty in tracking outbreaks from tomatoes once they occur. 

Tomatoes often spoil before officials can tie them to an outbreak and the fruit have an increasingly complicated supply chain, “it looks like a spider web on top of another spider web, on top of another spider web,” says Brown, who explains that accurately tracing back to the source of contamination is a difficult task. 

According to Brown, interventions are needed to prevent the harm to both public health and the economy, “Growers want positive intervention, we want positive intervention, and consumers need it.”

Photo by Helena Bottemiller.