Colicin genes in commensal and enterotoxigenic Escherichia coli isolates from the gastrointestinal tracts of pigs

摘要

The gastrointestinal tract (GIT) is made up of sections each performing a specific function. Within this GIT environment, there exists considerable diversity in gut microflora with bacteria competing with each other for nutrients as well as an ecological niche in each microhabitat. Commensal E. coli are normally the primary colonizers of the GIT and pathogenic E. coli must compete against this population to survive. Strategies used in this competition include more efficient assimilation of essentialnutrients, better ability to bind to receptors on the lumcnal face of intestinal epithelial cells and the production of anti-microbial compounds, such as bacteriocins that may inhibit or kill other bacteria. Colicins are bacterions produced by E. coli and other members of the family Enterobacteriacea such as Citrobacter and Shigella. The antimicrobial properties of colicins make them excellent candidates for use by commensal bacteria against pathogenic bacteria in the GIT. Therefore, it is important toassess whether commensal and pathogenic E. coli isolates differ in their ownership of colicin genes.