University of Wyoming researchers have discovered a substance that greatly increases the survival of Listeria monocytogenes, a foodborne bacterial pathogen that contaminates processed meat and milk products, as well as fresh produce.

Researchers hope the discovery will lead to the development of techniques to better combat the pathogen and to improve food safety.

Mark Gomelsky, a professor in UW’s Department of Molecular Biology, and other researchers discovered and characterized a substance, called exopolysaccharide (EPS), that Listeria secretes on its cell surface under certain conditions. The EPS coats bacterial cells and makes them form aggregates or clumps, which are strongly protected from commonly used disinfectants and desiccation (extreme drying).

“We think that EPS plays a significant role in survival of Listeria in the environment, during food storage, processing and transportation,” Gomelsky says. “Listeria rarely causes serious disease in healthy individuals but, in immune-compromised people, elderly and pregnant women, it can be deadly, causing as much as 20 percent to 25 percent mortality.”

Gomelsky is a senior writer of a paper, titled “Cyclic di-GMP-Dependent Signaling Pathways in the Pathogenic Firmicute Listeria monocytogenes,” that was published in Public Library of Science (PLoS) Pathogens Thursday.