Inhibitory combinations of nisin, sodium chloride, and pH on Listeria monocytogenes ATCC 15313 in broth by an experimental design approach.
The influence of pH (5.0-8.2), NaCl concentrations (0-6% w/v), and incubation time (0-24 h) on the inhibitory activity of nisin (0-100 I.U./ml) against Listeria monocytogenes (10(3) cfu/ml) was studied using the Doehlert experimental design and was confirmed by kinetic experiments. Predicted values were in agreement with experimental values. Experiments were carried out at 22 degrees C in reconstituted TSB-YE1 broth with or without NaCl. Nisin had an immediate pH-dependent bactericidal effect, which increased with decreasing pH values. In modified TSB-YE1 broth without NaCl, the bactericidal efficacy of nisin (50 I.U./ml) was maximum at pH 6.6, with no L. monocytogenes survivors until 120 h at 22 degrees C. Nisin (50 I.U./ml) action decreased in the presence of NaCl, with a minimal inhibitory effect between 2 and 4%. This partially protective effect was cancelled at higher levels of nisin.
Bouttefroy
A
A
Laboratoire de Fermentations et de Bioconversions Industrielles, Institut National Polytechnique de Lorraine, Ecole Nationale Supérieure d'Agronomie et des Industries Alimentaires (ENSAIA-INPL) 2, Vandoeuvre-Les-Nancy, France. bouttefr@ensaia.u-nancy.fr
Mansour
M
M
Linder
M
M
Milliere
J B
JB
D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D005516:Food Microbiology; D006863:Hydrogen-Ion Concentration; D008089:Listeria monocytogenes / Q000187:drug effects; D009561:Nisin / Q000494:pharmacology*; D012965:Sodium Chloride / Q000494:pharmacology*
D000900:Anti-Bacterial Agents; D009561:Nisin; D012965:Sodium Chloride