CALS Home | CALS news & events Chuck Kaspar -- Pound Research Award Whether he's collecting samples in a dairy barn or conducting sophisticated experiments in his lab, food microbiologist Charles Kaspar's goal is to learn enough about E. coli O157:H7 to bring today's most notorious food-safety threat under control. Since 1992, Chuck Kaspar and his colleagues have published 29 scientific articles about E. coli, making him a nationally and internationally respected authority. That research has revealed some of E coli's secrets, such as its hiding places on farms and the methods it uses to survive extreme conditions. For those discoveries and the insights they are producing about controlling this health threat, Kaspar is receiving the 2000 Pound Research Award. If there were a 10 most wanted list for food pathogens, E. coli would have vaulted to the top of the list in 1992. That year, more than 500 people in the Pacific Northwest became ill from eating E. coli O157:H7 in undercooked hamburgers made at a fast-food restaurant chain. In the collective minds of the public and media, E. coli remains today the most feared food-borne pathogen. Kaspar and his research team began their work on E. coli O157:H7 with a baseline survey of 70 Wisconsin dairy herds, finding no evidence of the bacterium on most farms. He later focused on a few farms with the problem to better understand the pathogen. "We wanted to find out how commonly it occurs on dairy farms, where it hides and how it gets from one animal to another," Kaspar says. To identify pathogenic strains and track where they were coming from, the researchers determined the genomic fingerprint of each O157:H7 strain they collected. Scientists have identified more than 100 strains of the E. coli O157:H7 serotype, based on differences in their genetic makeup. "Most farms with E. coli O157:H7 had a single dominant strain," Kaspar says. "That result indicates a single source followed by spread within a farm. We've seen that E. coli can hang around a farm for a long time, moving from animal to animal and through water back into the same animals again. There does not appear to be a common source, such as feed, across farms. "Drinking water is an important source of the bacterium in a herd," Kaspar says. "Once a source of drinking water became positive, cattle that drank the water began shedding the organism and it quickly spread to other nearby cattle." Kaspar has encouraging preliminary results that show that changing watering systems can reduce the prevalence of the bug from herds and farms where it has been found. The most publicized and largest E. coli outbreaks have involved contaminated ground beef. However, other outbreaks -- linked to apple cider, yogurt and dried fermented salami -- show the bug's impressive ability to protect itself from acid levels that kill most bacteria. Kaspar began investigating how the bacterium survives the acidic conditions common in the digestive systems of people and animals, as well as in processes used to make foods such as yogurt. He found that under certain conditions, many E. coli O157:H7 turn on a gene that arms them against acid, salt and heat. "Most E. coli O157:H7 strains can tolerate acid because they have the rpoS-regulated protection system. That regulator controls the production of approximately 50 proteins that protect the bacterium under environmental stresses," Kaspar says. If a bacterium can have an Achilles' heel, Kaspar would like to find it. His experiments show that he can fool the bacterium into dropping its armor, leaving it vulnerable to acid. He is also evaluating each of those 50 proteins to determine which enhance acid tolerance. Now Kaspar has begun studies of other bacterial systems that confer the ability to live under acidic conditions. He believes that research will help us understand more about the ecology of this and other acid-tolerant organisms.   George Gallepp   ### Top | CALS Home | CALS news & events CALS Press Service (608) 262-1461 Fax: (608) 265-3042