Unraveling the Listeria Genome

If knowledge is power, researchers are gaining the upper hand over Listeria monocytogenes, a pathogen that causes listeriosis.

Scientists at the Agricultural Research Service (ARS) Eastern Regional Research Center (ERRC) in Wyndmoor, Pa., and The Institute for Genomic Research in Rockville, Md., have sequenced the genomes of four L. monocytogenes strains, representing three serotypes—an important step towards developing a management strategy for this deadly bacterium.

Researchers in the ERRC Microbial Food Safety Research Unit and their colleagues have sequenced and analyzed these genomes, according to research leader John Luchansky.

With ERRC molecular biologist Darrell Bayles and research associate Gaylen Uhlich, Luchansky found that Listeria strains, in addition to sharing serotype-specific and strain-specific genome sequences, have largely similar genetic content and organization.

The scientists also confirmed that Listeria strains have 15 genes in the Crp/Fnr regulatory protein family, which is considerably more than most bacteria. Luchansky and his colleagues are investigating whether these sequences influence the bacterium’s virulence or persistence.

The scientists have identified specific genes that warrant further investigation. They’re also pursuing proteomics and genomics studies. This involves identifying phenotypes, or observable characteristics, understanding the relationships between different strains and investigating different control methods.

Knowing more about L. monocytogenes will help regulatory agencies and members of the food industry make informed decisions about control strategies and safety standards. In addition, uncovering the genetic information that defines Listeria’s characteristics and behavior will help scientists understand the bacterium’s virulence and persistence.

This research will be useful in preventing Listeria contamination and in reducing disease. It could also aid decisions about managing the threat of foodborne listeriosis.

Read more about this and other ARS food safety research in the October 2006 issue of Agricultural Research magazine.

ARS is the U.S. Department of Agriculture's chief scientific research agency.