Inactivation of Bacillus cereus by Na-chlorophyllin-based photosensitization on the surface of packaging.
OBJECTIVE
This study was focused on the possibility to inactivate food-borne pathogen Bacillus cereus by Na-chlorophyllin (Na-Chl)-based photosensitization in vitro and after attachment to the surface of packaging material.


RESULTS
Bacillus cereus in vitro or attached to the packaging was incubated with Na-Chl (7·5×10(-8) to 7·5×10(-5) mol l(-1) ) for 2-60min in phosphate buffer saline. Photosensitization was performed by illuminating cells under a light with a λ of 400nm and an energy density of 20mW cm(-2) . The illumination time varied 0-5min and subsequently the total energy dose was 0-6J cm(-2) . The results show that B. cereus vegetative cells in vitro or attached to the surface of packaging after incubation with 7·5×10(-7) mol l(-1) Na-Chl and following illumination were inactivated by 7log. The photoinactivation of B. cereus spores in vitro by 4log required higher (7·5×10(-6) mol l(-1) ) Na-Chl concentration. Decontamination of packaging material from attached spores by photosensitization reached 5log at 7·5×10(-5) mol l(-1) Na-Chl concentration. Comparative analysis of different packaging decontamination treatments indicates that washing with water can diminish pathogen population on the surface by <1log, 100ppm Na-hypochlorite reduces the pathogens about 1·7log and 200ppm Na-hypochlorite by 2·2log. Meanwhile, Na-Chl-based photosensitization reduces bacteria on the surface by 4·2 orders of magnitude.


CONCLUSIONS
Food-borne pathogen B. cereus could be effectively inactivated (7log) by Na-Chl-based photosensitization in vitro and on the surface of packaging material. Spores are more resistant than vegetative cells to photosensitization-based inactivation. Comparison of different surface decontamination treatments indicates that Na-Chl-based photosensitization is much more effective antibacterial tool than washing with water or 200ppm Na-hypochlorite.


CONCLUSIONS
Our data support the idea that Na-Chl-based photosensitization has great potential for future application as an environment-friendly, nonthermal surface decontamination technique.
Luksiene
Z
Z
Institute of Applied Research, Vilnius University, Vilnius, Lithuania. Zivile.Luksiene@tmi.vu.lt
Buchovec
I
I
Paskeviciute
E
E
D000890:Anti-Infective Agents / Q000494:pharmacology; D001409:Bacillus cereus / Q000187:drug effects* / Q000528:radiation effects*; D002735:Chlorophyllides / Q000494:pharmacology*; D003666:Decontamination / Q000379:methods*; D005511:Food Handling / Q000379:methods*; D008027:Light; D050296:Microbial Viability; D019064:Product Packaging
D000890:Anti-Infective Agents; D002735:Chlorophyllides; C007020:chlorophyllin