Content: The predator-prey interaction of Myxococcus xanthus and Escherichia coli is a well known microbial behavior, but has never been systematically investigated at the molecular level.In this study, we adapted a genetic screening assay originally developed for studying phagebacteria interactions to isolate and analyze M.xanthus mutants that are defective in this predatory behavior.Characterization of these mutants showed the importance of the M.xanthus genes involved in the biosynthesis of the polyketide antibiotic TA, which are transcriptionally upregulated in the presence of E.coli cells.