Abstract
Foods are spatially heterogeneous matrices in which microbial pathogens often grow as immobilised microcolonies rather than as freely suspended planktonic cells. We investigated how spatial growth in food-like semi-solid matrices affects responses to food-related stresses and subsequent tolerance to gastrointestinal conditions in eight major foodborne pathogens. Planktonic and spatialised populations were compared under salt and organic acid stresses. Spatial growth modified bacterial growth dynamics in a species-, stress- and concentration-dependent manner. More importantly, prior growth in gelled food-like matrices enhanced tolerance to simulated gastrointestinal stresses in vitro, particularly under acidic conditions. In Salmonella enterica, this protective effect was also observed in vivo in the acidic midgut of Hermetia illucens larvae, with significantly higher recovery (~ 2 log CFU/larva) after prior growth under high salt conditions. These findings show that spatial organisation can markedly modulate pathogen stress tolerance and should be considered in predictive microbiology and food safety assessment.
Subjects
- Ecology
- Microbiology
Acknowledgements
This research was funded by Aerial, INRAE, and “Association Nationale de la Recherche et de la Technologie” (contract 2023/0850). We thank the MIMA2 imaging platform (Microscopie et Imagerie des Microorganismes, Animaux et Aliments, https://doi.org/10.15454/1.5572348210007727E12) for the Leica SP8-HCS microscopy observations. Figure 3B was created with BioRender (https://biorender.com). Adrienne Lintz and Sarah Côte are acknowledged for technical assistance. Carlotta Savio is acknowledged for her help in developing the insect larval model. Cecile Berdous for technical assistance on larval dissections.
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Hoch, E., Nielsen-Leroux, C., Guillier, L. et al. Spatial growth of major foodborne pathogens in food-like matrices alters food-related stress responses and gastrointestinal tolerance.
npj Sci Food (2026). https://doi.org/10.1038/s41538-026-01006-z
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DOI: https://doi.org/10.1038/s41538-026-01006-z
Source: Ecology - nature.com
