Effect of environmental parameters (temperature, pH and aw) on the individual cell lag phase and generation time of Listeria monocytogenes

François, Kjell; Devlieghere, Frank; Standaert, A.R.; Impe, Jan Van; Debevere, Johan

doi:10.1016/j.ijfoodmicro.2005.11.017

Cited by 27 publications

(39 citation statements)

References 19 publications

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“…The E. coli distributions observed in the current study were slightly skewed toward higher division times, which is a common feature of lag distributions (6,7,9,12,20,26,31). It was not possible to assign any particular mathematical description to the distributions, since good fits to the data were found for a range of different functions and the histograms of division times lacked sufficient resolution to distinguish between them.…”

Section: Discussionmentioning

confidence: 67%

“…A wide range of distributions have been examined in other studies, but no one distribution has proven to be best for all stress conditions and environments. These include, for example, gamma (1,6,19), exponential (6), Weibull (6), lognormal (12,15), and extreme value (7,9,29) distributions. Given the diverse physiological effects of different stresses and the extreme sensitivity of stressed cells to small changes in their growth environment (13), it is not surprising that lag behavior fails to conform consistently to a mathematical ideal.…”

Section: Discussionmentioning

confidence: 99%

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Influence of Environmental Stress on Distributions of Times to First Division in Escherichia coli Populations, as Determined by Digital-Image Analysis of Individual Cells

Niven

Morton

et al. 2008

Appl Environ Microbiol

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The distributions of times to first cell division were determined for populations of Escherichia coli stationaryphase cells inoculated onto agar media. This was accomplished by using automated analysis of digital images of individual cells growing on agar and calculation of the "box area ratio." Using approximately 300 cells per experiment, the mean time to first division and standard deviation for cells grown in liquid medium at 37°C and inoculated on agar and incubated at 20°C were determined as 3.0 h and 0.7 h, respectively. Distributions were observed to tail toward the higher values, but no definitive model distribution was identified. Both preinoculation stress by heating cultures at 50°C and postinoculation stress by growth in the presence of higher concentrations of NaCl increased mean times to first division. Both stresses also resulted in an increase in the spread of the distributions that was proportional to the mean division time, the coefficient of variation being constant at approximately 0.2 in all cases. The "relative division time," which is the time to first division for individual cells expressed in terms of the cell size doubling time, was used as measure of the "work to be done" to prepare for cell division. Relative division times were greater for heat-stressed cells than for those growing under osmotic stress.When modeling the behavior of bacterial populations under different environmental conditions, the key kinetic parameters of the growth curve are the duration of the lag phase and the maximum specific growth rate. Lag time depends on both the environmental conditions and the physiological state of the inoculum and is thus more difficult to predict than growth rate, which, for a given organism, is an autonomous property defined by the environment alone (16,17). The lag times of cell populations are conventionally measured geometrically as the time at which a tangent to the point of maximum slope on a plot of log of bacterial concentration versus time crosses a horizontal projection of the inoculum concentration. However, when pathogenic bacteria are present in food, they are often found in very low numbers and the distribution of individual lag times within cell populations then becomes an important consideration in risk assessment.Lag time distributions can be determined directly by observing single cells under the microscope (5,11,22,25,32) or indirectly by measuring the time to produce a detectable optical density change in replicate cultures inoculated with approximately one cell using an automated growth analyzer such as the Bioscreen apparatus (7,12,19,26,29,31,32). An alternative indirect method consists of measuring the time to reach a certain colony size from single cells inoculated on an agar plate (8). Indirect methods are more convenient than microscopic methods and are essential when studying severely stressed populations containing only a few viable survivors.

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Section: Discussionmentioning

confidence: 67%

Section: Discussionmentioning

confidence: 99%

Influence of Environmental Stress on Distributions of Times to First Division in Escherichia coli Populations, as Determined by Digital-Image Analysis of Individual Cells

Niven

Morton

et al. 2008

Appl Environ Microbiol

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“…Since several lots of salmon and trout of this same manufacturer showed elevated levels of the pathogen, we notified the Public Health System of Navarra. Despite the fact that the majority of vacuum-packed products exhibited a label reading ''use by date" and ''store at 0-5°C", the truth is that many of the retail and domestic refrigerators are too warm for the safe storage of food (reaching temperatures P9°C) (Johnson et al, 1998), allowing the growth of the pathogen and other spoilage organisms in a shorter time (Francois et al, 2006). In addition, in-store-packaged products have not usually label information regarding recommended temperature and maximum storage time, leaving the establishment of the product shelf life up to the consumer.…”

Section: Contamination Levelmentioning

confidence: 99%

Survey of Listeria monocytogenes in ready-to-eat products: Prevalence by brands and retail establishments for exposure assessment of listeriosis in Northern Spain

2009

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“…However, foods are likely to be contaminated by low numbers of pathogenic bacteria and the cell to cell variability may become significant. Studies of the behaviour of single cells have been carried out during or after stress (Francois et al, 2006;Guillier & Augustin, 2006;Metris et al, 2008). As mentioned in the previous point, the stochastic nature of the kinetics of single cells presents a complex problem to risk assessors.…”

Section: Future Trendsmentioning

confidence: 99%

Predictive modelling of Salmonella: From cell cycle measurements to e-models

Muñoz-Cuevas

Métris

Baranyi

2012

Food Research International

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Effect of environmental parameters (temperature, pH and aw) on the individual cell lag phase and generation time of Listeria monocytogenes

Cited by 27 publications

References 19 publications

Influence of Environmental Stress on Distributions of Times to First Division in Escherichia coli Populations, as Determined by Digital-Image Analysis of Individual Cells

Influence of Environmental Stress on Distributions of Times to First Division in Escherichia coli Populations, as Determined by Digital-Image Analysis of Individual Cells

Survey of Listeria monocytogenes in ready-to-eat products: Prevalence by brands and retail establishments for exposure assessment of listeriosis in Northern Spain

Predictive modelling of Salmonella: From cell cycle measurements to e-models

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