Light-induced modulation of Porphyromonas gingivalis growth

Agnella D. Izzo, Joseph T. Walsh*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

13 Scopus citations


The bacterium Porphyromonas gingivalis is a clinically significant agent in periodontitis, a disease for which there is no definitive cure. Several groups have attempted to kill this bacterium using low levels of light in the absence of a photosensitizer, with conflicting results. We hypothesize that it is not possible to kill P. gingivalis by targeting endogenous porphyrins for a photochemical reaction. We demonstrated that irradiation of P. gingivalis with 455 or 625 nm light emitting diodes did not induce a photochemical killing of the cultures. Controlled temperature experiments indicate that irradiation at either wavelength did not significantly impact the growth of P. gingivalis cultures, as compared to non-irradiated controls. Rather, the irradiation caused a temperature increase in the growth medium, which altered the growth of the cultures. These results indicate that heat-induced killing of P. gingivalis could be the mechanism behind successful irradiation experiments with this bacterium.

Original languageEnglish (US)
Pages (from-to)63-69
Number of pages7
JournalJournal of Photochemistry and Photobiology B: Biology
Issue number1-3
StatePublished - Dec 2 2004
Externally publishedYes


  • Anaerobic bacterium
  • Endogenous porphyrin
  • Gram negative
  • Heme pathway
  • Oxygen
  • Photosensitization
  • Thermal response
  • Thermally labile

ASJC Scopus subject areas

  • Radiation
  • Radiological and Ultrasound Technology
  • Biophysics
  • Radiology Nuclear Medicine and imaging


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