Application of mathematical models for bacterial inactivation curves using Hypericin-based photosensitization

Abstract

AIMS: The aim of this study was to evaluate which of the three mathematical models (Weibull, Geeraerd and Logistic) makes the best approximation for Hypericin-based photosensitization bacterial inactivation. METHODS AND RESULTS: The inactivation of common food-borne pathogens Listeria monocytogenes and Bacillus cereus has been analysed. Three models, Weibull, Logistic and Geeraerd, have been used for different treatment conditions (10(-7 ) mol l(-1) and 10(-8) mol l(-1) Hypericin concentrations and 2 and 60 min incubation time). The Logistic method showed better correspondence (estimated R(2) ≥ 0·98, RMSE ≤ 0·41), than the Weibull (estimated R(2) ≥ 0·91, RMSE ≤ 0·90) and the Geeraerd model (R(2) ≥ 0·83, RMSE ≤ 1·27). After evaluation of best fitting model for the dependence of bacterial population reduction on irradiation time, the parameters describing treatment efficiency have been calculated. CONCLUSIONS: Our results indicate that the Logistic model described in the best way the inactivation of B. cereus and L. monocytogenes by Hypericin-based photosensitization. SIGNIFICANCE AND IMPACT OF THE STUDY: This study identified a best model for describing bacterial inactivation by hypericin-based photosensitization, which provides a way to evaluate the efficacy of different treatment conditions for this novel decontamination technique.