van der Donk Discovers New Antibiotic That Could Increase Food Safety

Date
12/31/12

Chemists led by Professor van der Donk has discovered a molecule very similar to the antibiotic nisin, found naturally in milk and added to food for decades to fight pathogenic bacteria. The new molecule geobacillin, is more stable than nisin, which could make it more effective.

The antibiotic nisin occurs naturally in milk, a product of bacteria resident in the cow’s udder. It helps keep milk from spoiling and kills a broad spectrum of bacteria that cause food-borne illness, most notably listeria and clostridium. It was approved as a food additive in 1969, and since then has become prevalent in the food industry in more than 50 countries.

Nisin also shows promise as a treatment for bovine mastitis, an infection in cows that costs the dairy industry billions each year since milk produced during and shortly after antibiotic treatment has to be thrown out. Since nisin already is present in low levels in milk, farmers using nisin to treat mastitis may not need to discard milk or meat from recently treated animals.

However, for all its utility, nisin has drawbacks. It’s produced in an acidic environment, but it becomes unstable at the neutral pH levels needed for many foods or pharmaceuticals. It also becomes unstable at higher temperatures, limiting its uses.

While studying the genome of another bacterium that lives at high temperatures, van der Donk’s group found genes to make a molecule with a similar structure and function to nisin, known as an analog. They isolated the genes and inserted them into E. coli so they could produce the new antibiotic, dubbed geobacillin, in large enough quantities to study its structure and function.

“As it turns out, geobacillin is more stable, both in respect to pH and temperature,” van der Donk said. “We think this is good news for potential use of geobacillin in food.”

Click here for the entire article from the UI News Bureau.

excerpted from an article by from Liz Ahlberg, UI News Bureau Physical Sciences Editor

Related People

vddonk