The antimicrobial activity of hop extracts obtained from different hop genotypes were investigated against and . In this study the pure xanthohumol, purified β-acids rich fraction, as well as α-acids with β-acids rich fraction were used to test antimicrobial activity against and ; whereby, the antimicrobial activity of different hop extracts against was studied for the first time. Microbial susceptibility to purified hydroacetonic extracts from different hop varieties was investigated by the broth microdilution assay to determine the minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC). The hop hydroacetonic extracts were more effective against than against . Strong inverse correlations of MIC and MBC values were obtained with xanthohumol, cohumulone, n+adhumulone, colupulone and n+adlupulone contents, suggesting that the identified chemical hop compounds are directly responsible for antimicrobial effects. Moreover, the effect of the growth medium strength on the MIC values of hop extracts against was systematically investigated for the first time. The current study also reveals the effect of different hop extracts on , which responds to their presence by lag phase extension and generation time prolongation.