Modelling the photosensitization-based inactivation of Bacillus cereus.
OBJECTIVE
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).


METHODS
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.


RESULTS
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).


CONCLUSIONS
The developed model proved to be a parsimonious and robust solution to describe the observed data.


CONCLUSIONS
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.
Marc
Y Le
YL
Institute of Food Research, Norwich Research Park, Norwich, UK. yvan.lemarc@bbsrc.ac.uk
Buchovec
I
I
George
S M
SM
Baranyi
J
J
Luksiene
Z
Z
D000622:Aminolevulinic Acid / Q000494:pharmacology*; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001409:Bacillus cereus / Q000187:drug effects* / Q000254:growth & development / Q000528:radiation effects; D015169:Colony Count, Microbial; D005519:Food Preservation / Q000379:methods; D008433:Mathematics; D008826:Microbial Sensitivity Tests; D050296:Microbial Viability / Q000187:drug effects; D008954:Models, Biological; D017319:Photosensitizing Agents / Q000494:pharmacology*; D013242:Sterilization / Q000379:methods*; D013997:Time Factors
D000900:Anti-Bacterial Agents; D017319:Photosensitizing Agents; D000622:Aminolevulinic Acid