Quantification of the effect of culturing temperature on salt-induced heat resistance of Bacillus species

H.M.W. den Besten, E.J. Mark, L. Hensen, T. Abee, M.H. Zwietering

Research output: Contribution to journalArticleAcademicpeer-review

13 Citations (Scopus)

Abstract

Short- and long-term exposure to mild stress conditions can activate stress adaptation mechanisms in pathogens, resulting in a protective effect toward otherwise lethal stresses. The mesophilic strains Bacillus cereus ATCC 14579 and ATCC 10987 and the psychrotolerant strain B. weihenstephanensis KBAB4 were cultured at 12°C and 30°C until the exponential growth phase (i) in the absence of salt, (ii) in the presence of salt, and (iii) with salt shock after they reached the exponential growth phase and subsequently heat inactivated. Both the first-order model and the Weibull model were fitted to the inactivation kinetics, and statistical indices were calculated to select for each condition the most appropriate model to describe the inactivation data. The third-decimal reduction times (which reflected the times needed to reduce the initial number of microorganisms by three decimal powers) were determined for quantitative comparison. The heat resistance of both mesophilic strains increased when cells were salt cultured and salt shocked at 30°C, whereas these salt-induced effects were not significant for the psychrotolerant strain. In contrast, only the psychrotolerant strain showed salt-induced heat resistance when cells were cultured at 12°C. Therefore, culturing temperature and strain diversity are important aspects to address when adaptive stress responses are quantified. The activated adaptive stress response had an even larger impact on the number of surviving microorganisms when the stress factor (i.e., salt) was still present during inactivation. These factors should be considered when stress-integrated predictive models are developed that can be used in the food industry to balance and optimize processing conditions of minimally processed foods
Original languageEnglish
Pages (from-to)4286-4292
JournalApplied and Environmental Microbiology
Volume76
Issue number13
DOIs
Publication statusPublished - 2010

Keywords

  • listeria-monocytogenes
  • thermal inactivation
  • cereus atcc-10987
  • genome sequence
  • acid tolerance
  • chilled foods
  • stress
  • anthracis
  • atcc-14579
  • outbreak

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