Partial purification and characterization of the bacteriocin produced by Propionibacterium jensenii B1264

Thirteen dairy propionibacteria were screened for catalase-insensitive, protease-sensitive inhibition of various Gram-positive and Gram-negative bacteria. Production of bacteriocin-like agents was identified in 8 of these cultures. The bacteriocin produced by Propionibacterium jensenii B1264 inhibited closely related propionibacteria and lactic acid bacteria and was bactericidal to Lactobacillus delbrueckii subsp. lactis ATCC 4797. It was produced in sodium lactate broth cultures during stationary phase; maximum activity was detected after 10 d of growth but only after 10-fold concentration of culture supernatants. The bacteriocin was precipated by ammonium sulphate at 70 % saturation. The ammonium sulphate-concentrated, dialyzed bacteriocin was stable to 0.1-1.0 mol.L-1 NaCl, 0.1-2.0 % SDS, 4 mol.L-1 urea, 100 degrees C (60 min), pH 2-10 and organic solvents (methanol, ethanol and isopropanol at 0-50 %). Batch anion exchange chromatography (pH 6.5) of the bacteriocin yielded 101 % activity and 15-fold increased purity. Flat bed analytical isoelectric focussing showed that the isoelectric point was between pH 3 and 3.5. SDS-PAGE yielded an estimated molecular mass between 6 and 9 kDa. The evidence suggests that this anionic bacteriocin is unique. (C) Inra/Elsevier, Paris.