Quantification of the effect of culturing temperature on salt-induced heat resistance of bacillus species.
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 degrees C and 30 degrees 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 degrees 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 degrees 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.
den Besten
Heidy M W
HM
Wageningen University and Research Centre, Laboratory of Food Microbiology, P.O. Box 8129, 6700 EV Wageningen, Netherlands. heidy.denbesten@wur.nl
van der Mark
Eric-Jan
EJ
Hensen
Lonneke
L
Abee
Tjakko
T
Zwietering
Marcel H
MH
D000222:Adaptation, Physiological; D001407:Bacillus / Q000145:classification / Q000187:drug effects / Q000254:growth & development / Q000502:physiology*; D001409:Bacillus cereus / Q000187:drug effects / Q000254:growth & development / Q000502:physiology; D003080:Cold Temperature; D015169:Colony Count, Microbial; D003470:Culture Media; D005525:Food-Processing Industry / Q000379:methods; D018869:Heat-Shock Response; D006358:Hot Temperature; D012965:Sodium Chloride / Q000378:metabolism / Q000494:pharmacology*; D013045:Species Specificity; D013696:Temperature
D003470:Culture Media; D012965:Sodium Chloride
Appl Environ Microbiol. 2006 Sep;72(9):5884-94
16957208
Nucleic Acids Res. 2004 Feb 11;32(3):977-88
14960714
Microbes Infect. 2000 Feb;2(2):189-98
10742691
FEMS Microbiol Rev. 2008 Jul;32(4):579-606
18422617
Int J Food Microbiol. 1999 Dec 1;53(1):61-7
10598115
J Bacteriol. 2004 Mar;186(6):1683-93
14996799
Appl Environ Microbiol. 2002 Jul;68(7):3486-95
12089032
Chem Biol Interact. 2008 Jan 30;171(2):236-49
17434157
J Appl Microbiol. 2001 Dec;91(6):1085-94
11851817
J Food Prot. 2006 Nov;69(11):2587-94
17133800
J Infect Dis. 1993 Jun;167(6):1452-5
8501338
J Clin Microbiol. 2005 Aug;43(8):4277-9
16082000
Nature. 2003 May 1;423(6935):87-91
12721630
Int J Food Microbiol. 2002 Nov 15;79(1-2):17-26
12382681
Int J Food Microbiol. 2008 Nov 30;128(1):165-73
18805600
Annu Rev Microbiol. 2009;63:451-76
19514852
Appl Environ Microbiol. 1991 Apr;57(4):1094-101
2059034
Int J Food Microbiol. 2002 Mar 25;74(1-2):139-59
11930951
Int J Food Microbiol. 2000 Sep 25;60(2-3):117-35
11016602
Appl Environ Microbiol. 2003 Dec;69(12):7514-6
14660405
Food Microbiol. 2008 Apr;25(2):294-303
18206772
J Appl Microbiol. 2002;92(3):404-14
11872115
Appl Environ Microbiol. 2009 Jun;75(12):4111-9
19395575
N Engl J Med. 1997 Apr 17;336(16):1142-8
9099658
Int J Food Microbiol. 2001 Feb 15;63(3):209-16
11246904