1 50 to 1 100 of the original volume of sterile distilled water concentrated supernatant was then dialyzed exhaustively against a 0 1m phosphate buffer having a ph of 6 8 activity of the p126 bacteriocin was assayed by two methods first the bacteriocin was spotted in 10 to 50 u03bcl portions onto nla plates containing an indicator lawn 10 4 to 10 5 cfu ml dried at 23 u00b0 c for 120 minutes and held at 32 u00b0 c for 48 hours additional assays were performed by the agar well diffusion method described by tagg and mcgiven in 34 assay system for bacteriocins 34 21 applied microbiology 943 1971 which is incorporated herein by reference in its entirety the titer of the p126 bacteriocin was defined as the reciprocal of the highest dilution inhibiting the indicator lawn and expressed as activity units au per milliliter the propionibacterium jensenii bacteriocin was examined for adsorption to p acidipropionici p5 and lactobacillus delbrueckii subsp lactis atcc 4797 one milliliter aliquots of overnight cultures of p acidipropionici p5 and l delbrueckii subsp lactis atcc 4797 were pelleted by centrifugation the cell pellets were washed twice in a 0 1m phosphate buffer having a ph of 6 8 resuspended in 0 1 ml of the bacteriocin 20 or 1 600 au ml against p acidipropionici p5 or l delbrueckii subsp lactis atcc 4797 respectively and held at 32 u00b0 c 37 u00b0 c and 4 u00b0 c replicates were removed at 0 1 2 3 4 5 6 12 and 24 hours cells were removed.