Papers by Florence Postollec
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International audienc
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International audienc
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Frontiers in Microbiology
Bacterial strains belonging to Lacticaseibacillus paracasei species are generally used as starter... more Bacterial strains belonging to Lacticaseibacillus paracasei species are generally used as starters in food fermentations and/or as probiotics. In the current study, the growth cardinal parameters of four L. paracasei strains (IMPC2.1, IMPC4.1, P40 and P101), isolated from table olives or human source, were determined. Strains were grown in liquid medium and incubated at several temperatures (10 values from 5.5°C–40°C) and pH (15 values from 3.2 to 9.1) along the growth range. The cardinal temperature model was used to describe temperature effects on the maximum specific growth rate of L. paracasei whereas new equations were developed for the effect of pH. The estimated Tmin values ranged between −0.97°C and 1.95°C and were lower than 0°C for strains IMPC4.1 and P101. Strain P40 was able to grow in the most restricted range of temperature (from 1.95°C to 37.46°C), while strain IMPC4.1 was estimated to survive at extreme conditions showing the lowest pHmin. Maximum specific growth rat...
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International audienc
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International Journal of Food Microbiology, 2022
The objective of this work is to match available phylogenetic information for Bacillus cereus str... more The objective of this work is to match available phylogenetic information for Bacillus cereus strains with published thermal resistance parameters (D90°C, z) and to use this information to develop refined inactivation models for B. cereus sensu lato. To do so, the thermal resistance parameters were retrieved for 57 strains of B. cereus that could be assigned to a phylogenetic group. This information was used to build specific distributions for D90°C and z for the different phylogenetic groups of B. cereus to build refined thermal inactivation models for B. cereus. For validation purposes, thermal parameters were also retrieved for additional strains of unknown groups, but which had been classified as psychrotrophic or mesophilic. Monte Carlo simulations were first performed assuming that the model parameters D90°C and z are independent. However, based on the observation that combinations of very high D90°C and high z-values were not reported, an alternative Monte Carlo simulation set was explored for the phylogenetic Groups with very high z-values (i.e.i.e. Groups IV and VI). With both simulation sets, the predicted lower and upper limits of the D-values are close to the lowest and highest D-values reported in two previous meta-analysis studies. However, a better correspondence between the predicted and observed limits is obtained when using the alternative simulation set.
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doi: 10.3389/fmicb.2013.00284 Bacillus cereus cell response upon exposure to acid environment: to... more doi: 10.3389/fmicb.2013.00284 Bacillus cereus cell response upon exposure to acid environment: toward the identification of potential biomarkers
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Applied and Environmental Microbiology, 2020
Changes with time of a population of Bacillus weihenstephanensis KBAB4 and Bacillus licheniformis... more Changes with time of a population of Bacillus weihenstephanensis KBAB4 and Bacillus licheniformis AD978 dormant spores into germinated spores and vegetative cells were followed by flow cytometry, at pH ranges from 4.7 to 7.4, and temperature from 10°C to 37°C for B. weihenstephanensis and from 18°C to 59°C for B. licheniformis. Incubation conditions lower than optimal temperatures or pH led to lower proportions of dormant spores able to germinate and extended time of germination, lower proportion of germinated spores able to outgrow, an extension of their times of outgrowth, and an increase of the heterogeneity of spore outgrowth time. A model based on the strain growth limits, was proposed to quantify the impact of incubation temperature and pH on the passage through each physiological stage. The heat-treatment temperature or time acted independently on spore recovery. Indeed, a treatment at 85°C during 12 min or at 95°C during 2 min did not have the same impact on spore germinatio...
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International Journal of Food Microbiology, 2018
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Food Microbiology, 2015
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International Journal of Food Microbiology, 2013
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International Journal of Food Microbiology, 2011
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International Journal of Food Microbiology, 2010
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Food Microbiology, 2012
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Food Microbiology, 2012
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Food Microbiology, 2012
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Food Microbiology, 2013
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Food Microbiology, 2013
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Papers by Florence Postollec