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Potatoes fight bacterial infections


Miami University microbiologist Marjorie (Kelly) Cowan and her laboratory have identified a substance in the potato that can fight infections.

This naturally occuring substance doesn’t kill bacteria, but rather prevents the microbes from attaching to human cells.

Cowan’s research interests in microbial adhesion led to her work with the potato. Potatoes have long been used in other cultures as a topical treatment of burns to help prevent the scarring caused by infections.

The potato works as an anti-infective, but has no bacterial killing capability. Cowan suspected that the potato extract could instead prevent attachment of microbes to human tissues. Her lab found that a water extract of potato inhibited the attachment of bacteria (oral streptococcus) to the tooth surface. The extract also prevented the attachment of the bacteria E. coli--which cause 90 percent of urinary tract infections--to host cells.

Cowan’s lab identified the anti-adhesive substance in the potato extract as the enzyme PPO, which is common in fruits and vegetables and is the chemical that causes them to turn brown as they age.

The study of anti-adhesives will become increasingly important as microorganisms become resistant to many antibiotics. "Without attachment to (human cells), 99 percent of infections can’t occur," explains Cowan.

Currently, plants are primarily tested for their ability to kill bacteria, a method that may rule out potentially important anti-adhesive substances. The approach studied by Cowan provides an alternative "kinder, gentler" method for the prevention of infections.

Working with Cowan on this study were Miami microbiology major Megan Gassert (graduated January 2000) and Ryan Terlecki, a microbiology major from Hillsdale College who worked in Cowan’s lab as a summer intern in 1999 through the Howard Hughes Medical Institute program.

Cowan is an assistant professor of microbiology at Miami Middletown. The research was presented at the 100th American Society for Microbiology meeting in May.


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