L. monocytogenes was propagated in PBN broth (pH 7.3) with the following components: 0.5% peptone, 0.3% beef extract, and 0.8% NaCl. H. pylori was propagated in a Tryptic soy agar (Difco, Sparks,MD, USA) with 5% defibrinated sheep blood added. To exclude the effect of lactic acid, antibacterial activity was laterconfirmed by pH adjustment (21).