Molecular Microbiology of Salmonella Typhimurium and E. Coli

Salmonella and E. coli are leading causes of food-borne bacterial infections which are causing significant problems in the UK. Because transmission and infection are dependent on the survival of bacteria in different environments such as water, soil and food, we are investigating the effect of environmental change on the expression of genes involved in infection. <P>
We are capitalising on the complete DNA genome sequence now available for E. coli, and will use the Salmonella genome sequence which is due in late 2000. Our functional genomic approach will use DNA microarrays and proteomic approaches to study bacterial genes that are switched on or off by environmental signals, or during the infection process. We are also investigating how Salmonella genes are switched on during infection by monitoring gene expression in individual Salmonella cells. This involves the use of Green Fluorescent Protein (GFP) as a reporter to give a visual indication of the switching on of particular genes during infection of mice, which is observed by microscopy or measured by flow cytometry.<P>
Our understanding of pathogenesis and environmental stress responses will open up new possibilities for the control or eradication of harmful bacteria in the food chain.