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Jellyfish Gene Helps Scientists Sleuth E. coli / March 29, 2000 / News from the USDA Agricultural Research Service

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A confocal scanning laser micrograph of fluorescent green E. coli gaining access to the xylem of cut leaf lettuce.

Read: details in Agricultural Research.

Jellyfish Gene Helps Scientists Sleuth E. coli

By Marcia Wood
March 29, 2000

To discover the secrets of how a food poisoning bacterium spreads, Agricultural Research Service scientists are using a jellyfish gene in their laboratory experiments.

In nature, the gene cues the jellyfish to make a bright green fluorescent protein. In the laboratory, ARS microbiologist Marian R. Wachtel has inserted the gene into strains of the foodborne pathogen Escherichia coli O157:H7. The fluorescence acts as a readily detectable marker.

Viewed with ultraviolet light, the E. coli fluoresces a bright green. The fluorescence makes it easier for Wachtel to spy on E. coli bacteria that she has used to artificially infect leaves of fresh lettuce for her experiments.

Outbreaks of E. coli O157:H7 linked to contaminated lettuce are infrequent. But ARS scientists like Wachtel want to help ensure that the popular vegetable remains safe to eat. Wachtel says eating fresh lettuce, properly washed, should pose no significant health hazard.

Wachtel's fluorescence based assay enables researchers to quickly detect the presence and quantity of the fluorescing E. coli within lettuce leaves. That's how the assay can help scientists test the effectiveness of new tactics designed to keep E. coli out of this veggie, and other foods, as well.

Though the idea of moving the fluorescence gene from Aequorea victoria jellyfish into other organisms isn't new, Wachtel is among the first to make a detailed study of plant tissue with fluorescent E. coli O157:H7 added.

Wachtel is with the ARS Food Safety and Health Research Unit at Albany, Calif. ARS is the U. S. Department of Agriculture's chief research branch.

For details, see an article in the agency's Agricultural Research magazine.

Scientific contact: Marian R. Wachtel, ARS Food Safety and Health Research Unit, Albany, Calif., phone (510) 559-5957, fax (510) 559-5948,

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