Temperature shock, injury and transient sensitivity to nisin in Gram negatives

Aims: The effect of thermal stresses on survival, injury and nisin sensitivity was investigated in Salmonella Enteritidis PT4, PT7 and Pseudomonas aeruginosa. Methods and Results: Heating at 55 degrees C, rapid chilling to 0.5 degrees C or freezing at -20 degrees C produced transient sensitivity to...

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Bibliographic Details
Published in:Journal of applied microbiology 2001-10, Vol.91 (4), p.715-724
Main Authors: Boziaris, I.S, Adams, M.R
Format: Article
Language:English
Subjects:
Anti-Bacterial Agents - pharmacology
Biological and medical sciences
Cold Temperature
cold treatment
Food industries
Food microbiology
Freezing
Fundamental and applied biological sciences. Psychology
heat
Heat-Shock Response
Hot Temperature
hydrophobicity
lipopolysaccharides
microbiological quality
nisin
Nisin - pharmacology
permeability
Pseudomonas aeruginosa
Pseudomonas aeruginosa - drug effects
Pseudomonas aeruginosa - growth & development
Pseudomonas aeruginosa - physiology
Salmonella Enteritidis
Salmonella enteritidis - drug effects
Salmonella enteritidis - growth & development
Salmonella enteritidis - physiology
Staphylococcus aureus
Surface Properties
temperature
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Summary:Aims: The effect of thermal stresses on survival, injury and nisin sensitivity was investigated in Salmonella Enteritidis PT4, PT7 and Pseudomonas aeruginosa. Methods and Results: Heating at 55 degrees C, rapid chilling to 0.5 degrees C or freezing at -20 degrees C produced transient sensitivity to nisin. Cells were only sensitive if nisin was present during stress. Resistance recovered rapidly afterwards, though some cells displayed residual injury. Injury was assessed by SDS sensitivity, hydrophobicity changes, lipopolysaccharide release and NPN uptake. LPS release and hydrophobicity were not always associated with transient nisin sensitivity. Uptake of NPN correlated better but persisted longer after treatment. Conclusions: Thermal shocks produce transient injury to the outer membrane, allowing nisin access. After treatment, the permeability barrier is rapidly restored by a process apparently involving reorganization rather than biosynthetic repair. Significance and Impact of the Study: Inclusion of nisin during food treatments that impose sub-lethal stress on Gram negatives could increase process lethality, enhancing microbiological safety and stability.
ISSN:1364-5072
1365-2672
DOI:10.1046/j.1365-2672.2001.01433.x