Modelling the photosensitization-based inactivation of Bacillus cereus

• Published in: Journal of applied microbiology Vol. 107; no. 3; pp. 1006 - 1011
• Main Authors: Marc, Y. Le, Buchovec, I, George, S.M, Baranyi, J, Luksiene, Z
• Format: Journal Article
• Language: English
• Published: Oxford, UK Oxford, UK : Blackwell Publishing Ltd 01.09.2009; Blackwell Publishing Ltd; Blackwell
• Subjects: Aminolevulinic Acid - pharmacology; Anti-Bacterial Agents - pharmacology; Bacillus cereus; Bacillus cereus - drug effects; Bacillus cereus - growth & development; Bacillus cereus - radiation effects; Biological and medical sciences; Colony Count, Microbial; Food Preservation - methods; Fundamental and applied biological sciences. Psychology; inactivation; Mathematics; Microbial Sensitivity Tests; Microbial Viability - drug effects; Microbiology; Models, Biological; photosensitivity disorders; photosensitization; Photosensitizing Agents - pharmacology; predictive model; Sterilization - methods; Time Factors; Weibull; Bacillus cereus; Weibull; predictive model; Bacillales; photosensitization; Applied microbiology; Bacteria; Models; Bacillaceae; Inactivation; Modeling
• ISSN: 1364-5072; 1365-2672
• DOI: 10.1111/j.1365-2672.2009.04275.x

To study and to develop a model for the photo-destruction of the foodborne pathogen Bacillus cereus, initially treated with a precursor of endogenous photosensitizers (5-aminolevulinic acid, ALA). The cells were incubated in the presence of ALA (3 or 7·5 mmol l⁻¹) for incubation times ranging from 2 to 60 min, inoculated onto the surface of LB Agar plates and submitted to light irradiation. The Weibull model was used to describe the survival curves of B. cereus. Quadratic equations were used to describe the effects of ALA concentration and incubation time on the Weibull model parameters. ALA-based photosensitization proved to be an effective tool for inactivation of B. cereus. The decrease in viable counts observed after 20 min of irradiation, ranged from 4 to 6 log CFU g⁻¹. The developed model proved to be a parsimonious and robust solution to describe the observed data. The study demonstrates the effectiveness of photosensitization on B. cereus on agar plates. The model developed may be useful to optimize inactivation treatments by photosensitization.