Comparison of Thermal Resistance of Clostridium botulinum and Its Surrogate Strain Clostridium sporogenes PA 3679

In a previous study, the thermal resistance of proteolytic Clostridium botulinum and its surrogate strain Clostridium sporogenes PA 3679 was compared by meta-analysis (Diao et al. 2014). A total of 911 D-values (time required to have a 10-fold decrease of the spore count) were collected from 38 scientific studies. It was shown that the heat resistance of proteolytic C. botulinum was significantly lower than the C. sporogenes PA 3679. For instance, at 121.1°C, the mean D_121.1°C of C. botulinum was estimated to 0.19 min, while C. sporogenes mean D_121.1°C was estimated to 1.28 min, in liquid media of neutral pH. Since data were collected over a range of heat-treatments from 100 to 145°C, z-values (temperature increase to have a 10-fold decrease of D-values) were also calculated. Finally, C. botulinum strain variability and residual error (i.e. uncertainty) were quantified. The difference in thermal resistance of C. botulinum and its surrogate strain, C. sporogenes, makes challenge tests performed for food processing validation difficult to interpret. The objective of this presentation is to tackle this issue by showing how pathogen behaviour could be predicted from the surrogate strain by taking variability and uncertainty into account.

Reference

Diao, M.M., André, S., Membré, J.-M., 2014. Meta-analysis of D-values of proteolytic Clostridium botulinum and its surrogate strain Clostridium sporogenes PA 3679. Int. J. Food Microbiol. 174:23-30.