Insights from Genomic Studies of the Foodborne and Waterborne PathogenEscherichia coliO157:H7

Abstract

In this chapter, the knowledge of the genome of E. coli O157:H7 may be used in the control of serious foodborne pathogen, E. coli strains are associated with gastrointestinal and extraintestinal illness. The E. coli O157:H7 genome provides us with information about the evolution and emergence of pathogen and the diversity that exists within populations of E. coli O157:H7. Most of E. coli prophage are defective and cannot form infectious phage. This chapter provides a brief review of subtyping methods used to characterize E. coli O157:H7 strains. Differences in biochemical utilization can be used to distinguish large categories of E. coli strain. Following the generation of cDNA from the bacteria’s mRNA using the enzyme reverse transcriptase, the level of gene expression is inferred from the intensity of the label signal from gene-specific microarray spots following hybridization. This procedure is the foundation of the new science of transcriptomics. Typically, quantitative PCR assays are also carried out on selected genes to measure mRNA levels to verify the significant changes in expression of genes observed in microarray-based transcriptomics studies. It is also evident that our understanding of E. coli O157:H7 gene regulatory systems will be enhanced through genomic sciences. E. coli O157:H7 and other bacterial pathogens have evolved through the acquisition of gene clusters borne on plasmids, bacteriophages, and genomic islands. Finally, with the arrival of the genomics revolution researchers are able to examine the pan-genome of the species and specific groups within species such as enterohemorrhagic E. coli(EHEC) and E. coli O157:H7.