Intraspecific Variability In Cardinal Growth Temperatures And Water Activities Within A Large Diversity Of Penicillium Roqueforti Strains

Different strains of a given fungal species may display heterogeneous growth behavior in response to environmental factors. In predictive mycology, the consideration of such variability during data collection could improve the robustness of predictive models. Among food-borne fungi, Penicillium roqueforti is a major food spoiler species which is also used as a ripening culture for blue cheese manufacturing. In the present study, we investigated the intraspecific variability of cardinal temperatures and water activities (aw), namely, minimal (Tmin and awmin), optimal (Topt and awopt) and maximal (Tmax) temperatures and/or aw estimated with the cardinal model for radial growth, of 29 Penicillium roqueforti strains belonging to 3 genetically distinct populations. The mean values of cardinal temperatures and aw for radial growth varied significantly across the tested strains, except for Tmax which was constant. In addition, the relationship between the intraspecific variability of the biological response to temperature and aw and putative genetic populations (based on microsatellite markers) within the selected P. roqueforti strains was investigated. Even though no clear relationship was identified between growth parameters and ecological characteristics, PCA confirmed that certain strains had marginal growth response to temperature or aw. Overall, the present data support the idea that a better knowledge of the response to abiotic factors such as temperature and aw at an intraspecific level would be useful to model fungal growth in predictive mycology approaches.