Spatial organisation of Listeria monocytogenes and Escherichia coli O157:H7 cultivated in gel matrices
2022
Saint Martin, Cédric | Darsonval, Maud | Grégoire, Marina | Caccia, Nelly | Midoux, Lucas | Berland, Sophie | Leroy, Sabine | Dubois-Brissonnet, Florence | Desvaux, Mickaël | Briandet, Romain | MICrobiologie de l'ALImentation au Service de la Santé (MICALIS) ; AgroParisTech-Université Paris-Saclay-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE) | Microbiologie Environnement Digestif Santé (MEDIS) ; Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Clermont Auvergne (UCA) | Paris-Saclay Food and Bioproduct Engineering (SayFood) ; AgroParisTech-Université Paris-Saclay-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE) | ANR-17-CE21-0002,PathoFood,Décrypter l'hétérogénéité cellulaire et la distribution spatiale de pathogènes dans les matrices alimentaires en interaction avec les communautés microbiennes(2017)
International audience
Show more [+] Less [-]English. The spatial organisation of bacterial pathogens in food matrices remains poorly understood, but is important in improving risk assessment and preventing infection of consumers by contaminated foodstuff. By combining confocal laser scanning microscopy with genetic fluorescent labelling of Listeria monocytogenes and Escherichia coli O157:H7, it was possible to investigate the spatial patterns of colonisation of both foodborne pathogens in gel matrices, alone or in combination, in various environmental conditions. Increasing low melting point agarose (LMPA) concentrations triggers the transition between a motile single-cell lifestyle to a sessile population spatially organised as microcolonies. The size, number and morphology of microcolonies were highly affected by supplementations in NaCl or lactic acid, two compounds frequently used in food products. Strikingly, single-cell motility was partially restored at higher LMPA concentration in the presence of lactic acid for Escherichia coli O157:H7 and in the presence of NaCl for Listeria monocytogenes. Co-culture of both species in the hydrogel affected pathogen colonisation features; Listeria monocytogenes was better able to colonise gel matrices containing lactic acid in the presence of Escherichia coli O157:H7. Altogether, this investigation provides insights into the spatial distribution and structural dynamics of bacterial pathogens in gel matrices. Potential impacts on food safety are discussed.
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