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USDA Research Agency Sequences Genome of Food-Borne Pathogen

By Marty Clark
June 7, 2001

WASHINGTON, June 7, 2001--The U.S. Department of Agriculture today announced that researchers now have important new information about the genetic makeup of Listeria, a bacterium that is known to cause serious food-borne illness. This new information will help in the research of ways to reduce the incidence of food contamination and illness from this bacterium.

The project is a collaboration between USDA’s Agricultural Research Service and The Institute for Genomic Research (TIGR) in Rockville, Md. Similar to efforts to understand the structure of the human genome, the researchers began examining the complete genetic makeup of a Listeria monocytogenes serotype 4b strain in January. The researchers have now finished the initial phase, in which individual fragments of the genome have been examined. The next step is to assemble these fragments into a complete genomic map of the bacterium.

A serotype 4b strain of Listeria monocytogenes was selected for the project because most food-borne listeriosis outbreaks, and 50 percent of sporadic cases, are caused by strains of this serotype.

The Listeria research is an example of ongoing USDA efforts to improve the safety of the U.S. food supply. Sequencing the Listeria genome will help researchers better understand how this bacterium persists in animals, in and on foods and in food processing plants, and affects people.

This information is critical for regulatory agencies such as USDA’s Food Safety Inspection Service for creating and implementing regulations for safe processing and handling of ready-to-eat foods.

USDA continues to make efforts to prevent contamination by Listeria, and other harmful pathogens, in ready-to-eat meat and poultry products. Recently, USDA proposed food safety measures applicable to all ready-to-eat and all partially heat-treated meat and poultry products, as well as environmental testing requirements intended to reduce the incidence of Listeria monocytogenes in processed meat and poultry products. The comment period has been extended until June 28.

In May, USDA's Food Safety and Inspection Service held a one-day technical conference and two days of public meetings to discuss scientific research and new technologies, and to gather public information and comments specific to proposed regulatory requirements for ready-to-eat meat and poultry products.

Listeria is widespread in the environment and is associated with some ready-to-eat food products such as hot dogs, lunch meats, smoked fish and certain types of soft cheeses. Each year, there are about 2,500 food-borne cases of listeriosis and about 500 deaths.

Scientists will be able to access the genetic sequence information through the TIGR website at after June 8. For additional food safety information, visit USDA's website at:

Scientific contact: John Luchansky, ARS Microbial Food Safety Research Unit, Wyndmoor, Pa., phone (215) 233-6620, fax (215) 233-6581,