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Effective inactivation of food pathogens Listeria monocytogenes and Salmonella enterica by combined treatment of hypericin‐based photosensitization and high power pulsed light
Author(s) -
Kairyte K.,
Lapinskas S.,
Gudelis V.,
Luksiene Z.
Publication year - 2012
Publication title -
journal of applied microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.889
H-Index - 156
eISSN - 1365-2672
pISSN - 1364-5072
DOI - 10.1111/j.1365-2672.2012.05296.x
Subject(s) - listeria monocytogenes , salmonella enterica , listeria , salmonella , microbiology and biotechnology , population , bacteria , hypericin , biology , chemistry , medicine , genetics , environmental health , pharmacology
Aims: The aim of this study was to evaluate the inactivation efficiency of Listeria monocytogenes ATC L3 C 7644 and Salmonella enterica serovar Typhimurium strain DS88 by combined treatment of hypericin (Hyp)‐based photosensitization and high power pulsed light (HPPL). Methods and Results: Cells were incubated with Hyp (1 × 10 −5 or 1 × 10 −7 mol l −1 ) in PBS and illuminated with a light λ = 585 nm. For the combined treatment, bacteria were, after photosensitization, exposed to 350 pulses of HPPL (UV light dose = 0·023 J cm −2 ). Fluorescence measurements were performed to evaluate optimal time for cell–Hyp interaction. Results indicate that Hyp tends to bind both Listeria and Salmonella . After photosensitization treatment, Listeria population was reduced 7 log, whereas Salmonella was inactivated just 1 log. Electron photomicrograps of Salmonella and Listeria confirmed that photosensitization induced total collapse of the Listeria cell wall, but not that of Salmonella . After combined photosensitization–HPPL treatment, the population of Listeria was diminished by 7 log and Salmonella by 6·7 log. Conclusions: Listeria can be effectively inactivated by Hyp‐based photosensitization (7 log), whereas Salmonella is more resistant to photosensitization and can be inactivated just by 1 log in vitro . Combined treatment of photosensitization and pulsed light inactivates effectively (6·7–7 log) both the Gram‐positive and the more resistant to photosensitization Gram‐negative bacteria. Significance and Impact of the Study: A new approach to combat Gram‐positive and Gram‐negative bacteria is proposed, combining photosensitization with high power pulsed light.