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

Dementavicius, D., Lukseviciute, V., Gómez‐López, V.M., Luksiene, Z.
Journal of applied microbiology 2016 v.120 no.6 pp. 1492-1500
Bacillus cereus, Listeria monocytogenes, decontamination, food pathogens, hypericin, irradiation, logit analysis, mathematical models, photosensitivity
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 R² ≥ 0·98, RMSE ≤ 0·41), than the Weibull (estimated R² ≥ 0·91, RMSE ≤ 0·90) and the Geeraerd model (R² ≥ 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.