| Popis: |
The sensitivities of vegetative cells of strains ofListeria, Clostridium, Staphylococcus, Lactococcus, Lactobacillus, MicrococcusandPediococcus, and of spores ofClostridiumandBacillusto three broad spectrum bacteriocins (nisin A, nisin Z and pediocin) from lactic acid bacteria were determined by a critical dilution micro-assay. The minimal inhibitory concentrations (MIC) of partially purified bacteriocins, prepared by a pH-dependent adsorption/desorption process, were determined and expressed in arbitrary units ml−1and in μ g ml−1of pure bacteriocin. The MICs of bacteriocins varied considerably between species and even between strains of the same species, as clearly shown for nine strains ofListeria monocytogenes. When bacteriocin activity was expressed in μ g ml−1, pediocin was more effective againstListeria monocytogenesthan nisin A or nisin Z. The latter bacteriocins, in concentrations between 23 and 69 μ g ml−1, prevented outgrowth ofClostridiumandBacillusspores for at least 10 days. Although pediocin at 17 μ g ml−1prevented outgrowth ofB. stearothermophilusandC. butyricumspores for up to 7 days, it apparently activated the germination ofB. subtilisspores. |
Full Text from ScienceDirect