Federal food safety scientists are waging biological warfare to combat salmonella in tomatoes.

Scientists with the Food and Drug Administration's Center for Food Safety and Applied Nutrition are studying naturally occurring bacteria that can fight the bacteria that causes salmonella and to keep tomatoes free from contracting the pathogen that causes the foodborne illness.

After attending a 2007 FDA meeting on tomato food safety, Eric Brown, an FDA microbiologist, said agency scientists decided they needed to develop ecologically friendly and efficient intervention strategies that would benefit growers.

“We really have a new and open area for food safety,” Brown said. “No one has really applied this premise to foodborne illnesses, particularly salmonella for tomatoes in the field.”

Brown said he and his small group of scientists have narrowed from 700 to five the number of “friendly” bacteria that has potential for becoming toxic against salmonella.

The scientists want to develop the bacteria that can be applied to commercial tomato farms.

Once released to industry, growers could add the fighting bacteria to sprayers and spray over crops a week or two before harvesting.

The surface sanitization would eradicate salmonella and other foodborne pathogens while on the vine before picking, Brown said.

The bacterial fighters, Brown said, can kill certain strains of E. coli as well as salmonella.

Brown said he and his scientists are working to show the biological weapons they have discovered can fight salmonella anywhere the pathogen has spread on a tomato, including on the surface, in the leaf scar of a just-harvested piece of fruit, on the flower or even inside in the tomato.

Brown said they see eradication of salmonella when they add the fighting bacteria in tests.

If they apply the friendly bacteria first, the decline is even more dramatic, he said.

“Salmonella can’t seem to get a foothold when our bug is present,” Brown said. “We are pleased to say that this has a broad spectrum in activity. We know these organisms are secreting and manufacturing or secreting toxic things to their neighbors. We characterize these toxins or bio-weapons because they hold the clue as to how they do the attacks against salmonella.”

The researchers want to remain focused on studying round reds, romas and cherry tomatoes — the leading varieties that remain susceptible to salmonella contamination, Brown said.

Once they can show an effect on plants in the FDA’s Beltsville, Md., greenhouses, they plan to release the science to industry and move onto other produce such as hot peppers and sweet peppers.

In the future, the scientists would likely collaborate with other FDA scientists to study bacteria that could fight pathogens such as E. coli in leafy greens. That research, Brown said, could be trickier because of the numerous layers in lettuce plants.

Study pits bacteria against salmonella in tomatoes

Courtesy Food and Drug Administration

Food and Drug Administration researchers are studying naturally occurring bacteria that fight salmonella.