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Sensitivity of nisin‐resistant Listeria monocytogenes to heat and the synergistic action of heat and nisin
Author(s) -
Modi K.D.,
Chikindas M.L.,
Montville T.J.
Publication year - 2000
Publication title -
letters in applied microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.698
H-Index - 110
eISSN - 1472-765X
pISSN - 0266-8254
DOI - 10.1046/j.1472-765x.2000.00708.x
Subject(s) - nisin , listeria monocytogenes , lactococcus lactis , bacteriocin , microbiology and biotechnology , food science , listeria , heat resistance , bacteria , chemistry , biology , antimicrobial , lactic acid , materials science , genetics , composite material
Nisin, a bacteriocin produced by some strains of Lactococcus lactis , acts against foodborne pathogen Listeria monocytogenes . A single exposure of cells to nisin can generate nisin‐resistant (Nis r ) mutants, which may compromise the use of nisin in the food industry. The objective of this research was to compare the heat resistance of Nis r and wild type (WT) Listeria monocytogenes . The synergistic effect of heat‐treatment (55 °C) and nisin (500 IU ml −1 ) on the Nis r cells and the WT L . monocytogenes Scott A was also studied. When the cells were grown in the absence of nisin, there was no significant (α = 0·05) difference in heat resistance between WT and Nis r cells of L . monocytogenes at 55, 60 and 65 °C. However, when the Nis r cells were grown in the presence of nisin, they were more sensitive to heat at 55 °C than the WT cells. The D ‐values at 55 °C were 2·88 and 2·77 min for Nis r ATCC 700301 and ATCC 700302, respectively, which was significantly (α = 0·05) lower than the D ‐value for WT, 3·72 min. When Nis r cells were subjected to a combined treatment of heat and nisin, there was approximately a four log reduction during the first 7 min of treatment.