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, Pennsylvania, and the Institute for Genomic Research in Rockville, Maryland, have sequenced the genomes of four L. monocytogenes strains representing three serotypes. Sequencing and analyzing these genomes is an important step toward developing a management strategy for this deadly bacterium.

Microbial Food Safety Research Unit Research Leader John Luchansky molecular biologist Darrell Bayles, and research associate Gaylen Uhlich of the ERRC Microbial Food Safety Research Unit have found that Listeria strains, in addition to sharing serotype-specific and strain-specific genome sequences, have largely similar genetic content and organization.

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

Specific genes that warrant further investigation have been identified. The scientists are also pursuing proteomics and genomics studies. This work 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 the food industry make informed decisions about control strategies and safety standards. Uncovering the genetic information that defines Listeria's characteristics and behavior also will help scientists understand the virulence and persistence of the bacterium.