Mechanisms of heat inactivation in Salmonella serotype Typhimurium as affected by low water activity at different temperatures

Aljarallah, Khalid M.; Adams, Martin R.

doi:10.1111/j.1365-2672.2006.03054.x

Cited by 50 publications

(29 citation statements)

References 26 publications

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“…Using laboratory models, it was demonstrated that reducing water activity either by desiccation (24,31) or by addition of solutes (2,12,30,37,38) resulted in increased thermal tolerance. Furthermore, low-water-activity medium (30) and dry environment (24) were found to enhance Salmonella tolerance to sodium hypochlorite and ethanol, respectively.…”

mentioning

confidence: 99%

Effect of Desiccation on Tolerance of Salmonella enterica to Multiple Stresses

Gruzdev

Pinto

Sela

2011

Appl Environ Microbiol

198

116

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Reducing the available water in food is a long-established method for controlling bacterial growth in the food industry. Nevertheless, food-borne outbreaks of salmonellosis due to consumption of dry foods have been continuously reported. Previous studies showed that dried Salmonella cells acquire high tolerance to heat and ethanol. In order to examine if dehydration also induces tolerance to other stressors, dried Salmonella enterica serotype Typhimurium cells were exposed to multiple stresses, and their viability was assessed. Indeed, desiccated S. Typhimurium acquired higher tolerance to multiple stressors than nondesiccated cells. The dried cells were significantly more resistant to most stressors, including ethanol (10 to 30%, 5 min), sodium hypochlorite (10 to 100 ppm, 10 min), didecyl dimethyl ammonium chloride (0.05 to 0.25%, 5 min), hydrogen peroxide (0.5 to 2.0%, 30 min), NaCl (0.1 to 1 M, 2 h), bile salts (1 to 10%, 2 h), dry heat (100°C, 1 h), and UV irradiation (125 W/cm 2 , 25 min). In contrast, exposure of Salmonella to acetic and citric acids reduced the survival of the dried cells (1.5 log) compared to that of nondesiccated cells (0.5 log). Three other S. enterica serotypes, S. Enteritidis, S. Newport, and S. Infantis, had similar stress responses as S. Typhimurium, while S. Hadar was much more susceptible and gained tolerance to only a few stressors. Our findings indicate that dehydration induces cross-tolerance to multiple stresses in S. enterica, demonstrating the limitations of current chemical and physical treatments utilized by the food industry to inactivate food-borne pathogens.

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mentioning

confidence: 99%

Effect of Desiccation on Tolerance of Salmonella enterica to Multiple Stresses

Gruzdev

Pinto

Sela

2011

Appl Environ Microbiol

198

116

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“…All experiments were performed at least in triplicate. The procedures used in this study were similar to those described by Aljarallah and Adams (2007). After incubation, cfu on the agar plates were counted manually.…”

Section: Methodsmentioning

confidence: 99%

“…Previous studies done by Wuytack et al (2003) have shown similar results for Salmonella under thermal treatment. Based on these results it can be concluded that irreversible outer membrane and cytoplasmic membrane permeabilization is the major cause of cell death (Aljarallah and Adams 2007;Mackey 2000), and prone to cause sublethal injury (Garcia et al 2005).…”

Section: Comparison Of Thermal-resistance Of Cells In Exponential Andmentioning

confidence: 99%

Inactivation and occurrence of sublethal injury of Salmonella Typhimurium under mild heat stress in broth

Suo

Shi

2012

J. Verbr. Lebensm.

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Thermal processing of food products continues to be the standard commercial method used for enhancing microbiological safety. The influence of cell characteristics of Salmonella Typhimurium strains, such as growth phase, cell density, and the availability of nutrients and metabolites was evaluated regarding a 3 Log 10 reduction of surviving cells when exposed to a mild heat treatment of 55°C. Using nonselective and selective agars it was revealed that under thermal stress Salmonella Typhimurium suffered from injuries on both outer and cytoplasmic membrane, which consequently led to cell death. Compared to stationary cells, those in exponential growth phase were more prone to thermal injury, especially on the cytoplasmic membrane. Occurrence of thermal inactivation and injury decreased with the increase of cell density, and with the increased availability of metabolites produced during cell growth, but showed no apparent correlation with nutrients in the culture broth. The results enlighten the importance of cell growth phase, cell density and metabolite availability in Salmonella Typhimurium thermal resistance. Consequently these factors should be well considered when models are constructed and used to predict thermal effects on the survival of the pathogen. Moreover, our data show that attention should be paid when selective media are used to detect sublethally injured cells.

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“…Exposures to IJFS October 2017 Volume 6 pages 139-151 acidic environments are also known to induce disruption of biochemical processes within the cells such as enzymes functions and nutrient transport (Beales, 2004). At higher temperatures, the study of Aljarallah and Adams (2007) showed that ribosomal inactivation was a primary target of cell damage.…”

Section: Effect Of Plating Mediamentioning

confidence: 99%

nfluences of physicochemical stresses on injury and inactivation behaviour of Listeria innocua

Miller

Ramos

Gil

et al. 2017

IJFS

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Many minimally processed foods depend on a combination of inhibitory factors to reduce the hazard of foodborne illness. Therefore, inactivation of Listeria innocua was studied according to a 2 4 factorial experiment designed to draw conclusions about temperature (52.5°C and 65.0°C), pH (4.5 and 7.5), water activity (aw=0.95 and 0.99) and solute type (NaCl and glycerol) effects. Three different recovery media were used to assess injured cells. Survival data were fitted with a Gompertz-based model and kinetic parameters (shoulder, maximum inactivation rate -kmax, and tail) were estimated. Results showed that shoulder was affected by temperature, pH and combined effects; kmax was influenced by all factors and their combinations; and tail was affected by aw, temperature and aw/pH combination. Results demonstrated the potential occurrence of microbial cross-protection survival techniques between the various stresses, e.g. heat and osmolarity. Indeed, this work clearly established that, to avoid hazards, Listeria inactivation must be evaluated with a maximum of environmental factors that undergo alterations. Only thus, appropriate food preservation treatments can be developed and consequently, the safety of food products can be assured.

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Mechanisms of heat inactivation in Salmonella serotype Typhimurium as affected by low water activity at different temperatures

Cited by 50 publications

References 26 publications

Effect of Desiccation on Tolerance of Salmonella enterica to Multiple Stresses

Effect of Desiccation on Tolerance of Salmonella enterica to Multiple Stresses

Inactivation and occurrence of sublethal injury of Salmonella Typhimurium under mild heat stress in broth

nfluences of physicochemical stresses on injury and inactivation behaviour of Listeria innocua

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