Modeling microbial competition in food: Application to the behavior of Listeria monocytogenes and lactic acid flora in pork meat products

Cornu, Marie; Billoir, Élise; Bergis, H.; Beaufort, Annie; Zuliani, Véronique

doi:10.1016/j.fm.2010.08.007

Cited by 111 publications

(63 citation statements)

References 58 publications

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“…The so-called "dominant" bacterial species rapidly reached the stationary phase at a concentration of between 8 and 9 log CFU/g while at the same time the "inhibited" strains stopped their growth at a lower concentration. This phenomenon was described by Jameson in 1962 and recently reviewed by other scientists as follows: "the minority population decelerates when the majority or the total population count reaches its maximum" (Ross et al, 2000;Mellefont et al, 2008;Irlinger and Mounier, 2009;Cornu et al, 2011). This Jameson effect was clearly observed in our study, for example at 4°C (Table 2), when Lc.…”

Section: Discussionsupporting

confidence: 78%

“…This pattern is described for all storage conditions with the same strain classifications (Table 2). This phenomenon was also observed by others scientists and they proposed that the growth of the minority population is only partly inhibited after the majority population has reached its stationary phase (Gnanou Besse et al, 2006;Cornu et al, 2011). This can be explained by the fact that the minority population is only partly affected by the limiting resource and/or inhibiting waste product that led it to stop growing (Gnanou Besse et al, 2006;Cornu et al, 2011).…”

Section: Discussionsupporting

confidence: 54%

“…Further studies will focus on the comprehension of the mechanisms that force the "inhibited" strains to stop their growth in the early stage of the shelf life of the product. Indeed, it is commonly accepted that the self-limiting growth process in microbial ecosystem is supposed to be due to (i) the exhaustion of one of the essential nutrients, (ii) the accumulation of metabolic waste products which inhibit growth, and/or (iii) the lowering of pH due to acid production (Cornu et al, 2011). According to the data already obtained, we could suppose that competition for space or nutrient has an effect.…”

Section: Discussionmentioning

confidence: 99%

See 2 more Smart Citations

The use of 16S rRNA gene metagenetic monitoring of refrigerated food products for understanding the kinetics of microbial subpopulations at different storage temperatures: the example of white pudding

Cauchie

Gand

Kergourlay

et al. 2017

International Journal of Food Microbiology

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In order to control food losses and wastage, monitoring the microbial diversity of food products, during processing and storage is important, as studies have highlighted the metabolic activities of some microorganisms which can lead to spoilage. Knowledge of this diversity can be greatly improved by using a metagenetic approach based on high throughput 16S rRNA gene sequencing, which enables a much higher resolution than culture-based methods. Moreover, the Jameson effect, a phenomenon described by Jameson in 1962, is often used to classify bacterial strains within an ecosystem. According to this, we have studied the bacterial microbiota of Belgian white pudding during storage at different temperatures using culture-dependent and independent methods. The product was inoculated with a mix of dominant strains previously isolated from this foodstuff at the end of its shelf life (Carnobacterium maltaromaticum, Lactobacillus fuchuensis, Lactobacillus graminis, Lactobacillus oligofermentans, Lactococcus lactis, Leuconostoc mesenteroides, Raoultella terrigena and Serratia sp.). Daily during 16 days, the absolute abundance of inoculated strain was monitored by combining total count on plate agar and metagenetic analysis. The results were confirmed by qPCR analysis. The growth of each species was modelled for each temperature conditions, representative of good or bad storage practices. These data allowed the bacterial strains subdivision into three classes based on criteria of growth parameters for the studied temperature: the "dominant", the "subdominant" and the "inhibited" bacterial species, according to their maximal concentration (Nmax, log CFU/g), growth rate (μmax, 1/h) and time to reach the stationary phase (TRSP, days). Thereby, depending on the storage conditions, these data have permitted to follow intrinsically the evolution of each strain on the bacterial ecosystem of Belgian white pudding. Interestingly, it has shown that the reliability of the Jameson effect can be discussed. For example, at 4°C when Lactococcus lactis and Serratia sp. stopped growth at day 12, at the same time Carnobacterium maltaromaticum reached its maximal concentration and entered its stationary phase. In opposition to this, it can be noticed that in the same condition, the "sub-dominant" organisms continued their growth independently of the "dominant" species behaviour. In this case, the Jameson effect was not illustrated. This pattern is described for all storage conditions with the same strain classifications. These results highlighted the importance of combining metagenetic analysis and classical methods, with modelling, to offer a new tool for studying the evolution of microorganisms present in perishable food within different environmental conditions.

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Section: Discussionsupporting

confidence: 78%

Section: Discussionsupporting

confidence: 54%

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

The use of 16S rRNA gene metagenetic monitoring of refrigerated food products for understanding the kinetics of microbial subpopulations at different storage temperatures: the example of white pudding

Cauchie

Gand

Kergourlay

et al. 2017

International Journal of Food Microbiology

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“…Since the naturally microbiota can influence the growth rate of L. monocytogenes, a characterization of the products as related to their producers was made to evaluate the variability of typical bacteria counts (Cornu et al 2011). The products were analysed to evaluate typical microbiota as total count, lactic acid bacteria (LAB), Staphylococcus Non Coagulase Positive (NCP), Enterobacteriaceae, yeasts and the absence of any typical Listeria colonies.…”

Section: Microbial Challenge Test (Mct) 231 Product Characterizatimentioning

confidence: 99%

Listeria monocytogenes on cured meat products. A case study on Speck (a typical Italian smoked ham) according to EC Regulation 2073/2005

Barbuti¹,

Dalzini²,

Frustoli³

et al. 2017

SDRP-JFST

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ABSTRACT:Ready To Eat (RTE) meat products may be able to support the growth of Listeria monocytogenes during their shelf life. In agreement with the European Commission (EC) Regulation N. 2073/2005 on microbiological criteria for foodstuff, the products with pH ≤ 4.4 or aw ≤ 0.92, those with pH ≤ 5.0 and aw ≤ 0.94 and those with a shelf-life of less than five days are automatically included in the category of RTE foods that doesn't able to support the growth of L. monocytogenes. Otherwise, the manufacturers must demonstrate whether their products not allow the growth of L. monocytogenes by use of different approaches based on: i) physicalchemical analyses of product, ii) predictive microbiology and iii) Microbial Challenge Test (MCT), as suggested by EC Regulation 2073/2005. The present study evaluated the three above mentioned approaches on Speck, a traditional smoked dry cured ham produced in South Tyrol (Italy). Both the variability of the physical-chemical properties of Speck (aw ranging from 0.890 to 0.940 and pH from 5.37 to 6.24) and the use of prediction models did not allow to state whether the product supports the growth of the pathogen and a reliable classification of the product. On the contrary, the MCT carried out showed the L. monocytogenes inactivation during shelf life of sliced vacuum-packed or modified atmosphere-packed Speck stored at different temperatures 4°, 8° and 20°C.

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“…A high background flora on plates might strongly influence the growth of target organisms. This, as well as the methodological problem of low-occurrence of pathogens, is frequently discussed in the literature [12-14]. A direct plating approach, to quantify low numbers of target cells, has not been used in clinical diagnostics until now.…”

Section: Introductionmentioning

confidence: 99%

Quantification of Gram-positive bacteria: adaptation and evaluation of a preparation strategy using high amounts of clinical tissue

et al. 2014

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BackgroundA preparation method for quantification of bacteria in tissues is obligatory to reduce tissue mass, concentrate the target, purify, remove inhibitory substances and to achieve constant target recovery rates. No preparation method has been available until now for a high mass of tissue applicable for routine use and analytical veterinary diagnostics.ResultsThis study describes an easy-to-use tissue preparation protocol to quantify Gram-positive bacteria from a large volume of tissue matrix. A previously published sample preparation method (Matrix-Lysis) from food science was successfully adapted for clinical use on tissues from pigs, including cerebrum, spinal cord, lung, liver, ileum, colon, caecum, kidney and muscle tissue. This tissue preparation method now permits quantification of pathogens from 5 g of organic matrix, which is a 20–200 fold increase by weight compared to other methods. It is based on solubilization of the sample matrix with either a chaotrope plus detergent or divalent salts as solubilization agents. The method was designed as a modular system, offering the possibility to change lysis buffers, according to tissue solubilization characteristics and the intended detection method (molecular or culture). Using Listeria monocytogenes as model organism, viable cell quantification or DNA extraction and quantitative real-time PCR were performed after Matrix-Lysis to determine recovery rates and detection limit (LOD). The adapted Matrix-Lysis protocol resulted in high recovery rates (mean value: 76% ± 39%) for all tested organs, except kidney, and recovery was constant over 5 log scales for all tested buffer systems. The LOD for Matrix-Lysis with subsequent plate count method (PCM) was as low as 1 CFU/5 g, while for qPCR based detection the LOD was 102 bacterial cell equivalents (BCE)/5 g for two buffer systems.ConclusionsThis tissue preparation is inexpensive and can be easily used for routine and analytical veterinary diagnostics. Inoculation studies or hazard assessments can profit from this tissue preparation method and it is anticipated that this study will be a valuable source for further research on tissue preparation strategies.

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Modeling microbial competition in food: Application to the behavior of Listeria monocytogenes and lactic acid flora in pork meat products

Cited by 111 publications

References 58 publications

The use of 16S rRNA gene metagenetic monitoring of refrigerated food products for understanding the kinetics of microbial subpopulations at different storage temperatures: the example of white pudding

The use of 16S rRNA gene metagenetic monitoring of refrigerated food products for understanding the kinetics of microbial subpopulations at different storage temperatures: the example of white pudding

Listeria monocytogenes on cured meat products. A case study on Speck (a typical Italian smoked ham) according to EC Regulation 2073/2005

Quantification of Gram-positive bacteria: adaptation and evaluation of a preparation strategy using high amounts of clinical tissue

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