Intraspecific variability in heat resistance of fungal conidia

Tom van den Brule, Maarten Punt, Sjoerd J. Seekles, Frank J.J. Segers, Jos Houbraken, Wilma C. Hazeleger, Arthur F.J. Ram, Han A.B. Wösten, Marcel H. Zwietering, Jan Dijksterhuis, Heidy M.W. den Besten*

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review


Microbial species are inherently variable, which is reflected in intraspecies genotypic and phenotypic differences. Strain-to-strain variation gives rise to variability in stress resistance and plays a crucial role in food safety and food quality. Here, strain variability in heat resistance of asexual spores (conidia) of the fungal species Aspergillus niger, Penicillium roqueforti and Paecilomyces variotii was quantified and compared to bacterial variability found in the literature. After heat treatment, a 5.4- to 8.6-fold difference in inactivation rate was found between individual strains within each species, while the strain variability of the three fungal species was not statistically different. We evaluated whether the degree of intraspecies variability is uniform, not only within the fungal kingdom, but also amongst different bacterial species. Comparison with three spore-forming bacteria and two non-spore-forming bacteria revealed that the variability of the different species was indeed in the same order of magnitude, which hints to a microbial signature of variation that exceeds kingdom boundaries.

Original languageEnglish
Article number111302
Pages (from-to)1-9
Number of pages9
JournalFood Research International
Publication statusPublished - Jun 2022


  • Aspergillus niger
  • Food spoilage
  • Paecilomyces variotii
  • Penicillium roqueforti
  • Strain variability
  • Thermal inactivation kinetics


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