Abstract
Thermal inactivation curves of Aspergillus niger spores and mycelia in phosphate-citrate buffer were studied. Spores were most thermoresistant when suspended at pH 5.0 out of a range of pH 4.0-9.0. At higher salt (sodium chloride) concentrations of 0-0.7 M spores were more resistant. These curves were well described by a thermotolerant subpopulation model and characterized with the parameter values of the model. Catalase and pyruvic acid supplemented in enumeration media or heating menstruum did not raise the survival ratios of heated spores. The thermal inactivation curve of mycelia did not have a shoulder but a tail.
