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Medium is Well Done for Detecting Harmful Salmonella

By Jill Lee
August 4, 1997

In movies, the cops sometimes get the bad guys to confess by making them comfortable--easing them into disclosing their guilt.

Now, a USDA scientist can coax Salmonella bacteria, food-safety culprits in poultry, into spilling their well-kept secrets. J. Guard Petter, with USDA’s Agricultural Research Service at Athens, Ga., does this with a new laboratory growth medium.

Bacteria exposed to the new medium make more proteins and carbohydrates connected with causing illness and egg contamination. It even works for strains that normally don’t make these proteins. This means researchers could discover if a bacterium now considered harmless has a potentially dangerous side.

Researchers have considered a growth medium successful if it doubled protein production. The new medium increases production an average of ten fold. ARS has applied for a patent, and the researchers seek to expand the technology’s applications beyond detecting food pathogens.

For example, using the medium to “mine” bacterial cells for hard-to-find proteins could help lead to new vaccines. The medium might also improve existing vaccines, especially those using dead bacteria to boost immunity. Drug companies could evaluate protein quality before harvesting a candidate bacterium. This could ensure more consistency from one drug batch to the next.

The medium could also improve safety of vaccines made with a live though harmless form of a bacterium. Researchers could test the bacterium’s potential to revert to a disease-causing form.

The new medium’s ability to make cells express proteins longer than usual may also help medical researchers studying diseases caused by genes turning on at the wrong time.

Scientific contact: J. G. Petter, USDA/ARS Southeast Poultry Research Laboratory, Athens, Ga. Phone: (706) 546-3446, fax (706) 546-3161 e-mail: