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Although Listeria can grow at the body temperature of an infected person, it has the unusual ability to also grow at refrigeration temperatures. Refrigeration can then in effect increase the Listeria content of a food. We are interested in the underlying mechanisms involved that permit the bacterium to grow at low temperatures.
The bacterium Listeria monocytogenes is the causative agent of the foodborne disease listeriosis. The fatality rate of listeriosis is high and it is believed to be the leading cause of death from foodborne infections in the United States. Although Listeria can grow at the body temperature of an infected person, it has the unusual ability to also grow at refrigeration temperatures. Refrigeration can then in effect increase the Listeria content of a food. We are interested in the underlying mechanisms involved that permit the bacterium to grow at low temperatures. We will attempt to identify novel genes and proteins involved in growth at low temperatures. A fatty acid known as anteiso branched chain fatty acid appears to play a critical role in growth at low temperatures. We will investigate the role of this fatty acid in maintaining membrane lipid fluidity at refrigeration temperatures. During food processing bacteria can become injured and undetectable by conventional culturing methods, but not be dead. We suspect that injured bacteria contain denatured proteins that must be degraded before the bacteria can grow, and we will investigate this hypothesis. It is hoped that these studies will provide the scientific basis that will lead to novel methods of control of Listeria and improved methods of detection of the organism.