ARS | Publication request: DEVELOPMENT AND DEMONSTRATION OF RNA ISOLATION AND RT-PCR PROCEDURES TO DETECT ESCHERICHIA COLI O157:H7 GENE EXPRESSION ON BEEF CARCASS SURFACES

Submitted to: Letters in Applied Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 25, 2000
Publication Date: October 1, 2000
Citation: Berry, E.D. 2000. Development and demonstration of RNA isolation and RT-PCR procedures to detect Escherichia coli O157:H7 gene expression on beef carcass surfaces. Letters in Applied Microbiology. 31:265-269.

Interpretive Summary: Some food poisoning bacteria are able to adapt and become resistant to the processing procedures and preservatives we use to inactivate them or to inhibit their growth in foods. This adaptation process typically involves changing bacterial gene expression, by switching particular genes on or off, or by changing levels of expression of particular genes. Preventing the development of pathogen resistance to food processing and preservation will require understanding the gene expression changes that the bacteria make in order to adapt and become tolerant. In this work, reverse transcription-polymerase chain reaction (RT-PCR) procedures were developed as tools to detect and study gene expression of bacteria on the surfaces of beef carcasses. RT-PCR is a very sensitive technique that is used to detect genes only when they are being expressed. The utility of these procedures was demonstrated by detecting the expression of a gene that can be selectively switched on in a special strain of the pathogen Escherichia coli O157:H7, when this bacterium was present on beef carcass surface tissue. These procedures should serve as useful tools for studying the gene expression responses of bacteria when they are exposed to antimicrobial treatments that are applied to food animal carcasses.

Technical Abstract: Preventing the development of pathogen resistance to processing and preservation techniques will require understanding the genetic mechanisms that pathogens utilize in situ to adapt and develop tolerance to stresses they encounter in the food environment. RNA isolation and reverse-transcription (RT)-PCR protocols were developed as tools to detect gene expression in bacteria on beef carcass surfaces. The utility of these procedures was demonstrated by detecting the expression of a selectively inducible green fluorescent protein (GFP) gene in a plasmid-transformed strain of Escherichia coli O157:H7 inoculated onto beef carcass surface tissue. These procedures should serve as useful tools for studying the genetic responses of bacteria when exposed to antimicrobial interventions that are applied to food animal carcasses.