Because V52 exhibited the highest killing efficiency toward E. coli, we selected E. coli K-12 as experimental prey for future experiments. Rifampicin-resistant E. coli MG1655 prey was mixed with a rifampicin-sensitive predator, either self or V.cholerae strain V52, in a killing assay described in Materials and Methods. When E. coli was mixed with rifampicin-sensitive self, E. coli survival was on the order of 108 colony-forming units (cfu)·mL−1 (Fig. 2A). Remarkably, in the presence of the V52 predator, up to a 100,000-fold reduction in culturable E. coli was observed (Fig. 2A). The dramatic virulence exhibited by V52 was