This is the first report on the fate of enterohemorrhagic Escherichia coli O157:H7 in simulated human colonic conditions. The pathogen was progressively eliminated from the bioreactor and did not modify the major populations of resident microbiota. The coadministration of the Saccharomyces cerevisiae CNCM I-3856 probiotic strain led to a significant increase in acetate production but did not reduce pathogen viability.