Photo-dynamic biocidal action of methylene blue and hydrogen peroxide on the cyanobacterium Synechococcus leopoliensis under visible light irradiation

Cathy McCullagh, Peter K J Robertson*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

14 Citations (Scopus)


Biofilm growth on stone surfaces is a significant contributing factor to stone biodeterioration. Current market based biocides are hazardous to the environment and to public health. We have investigated the photo-dynamic effect of methylene blue (MB) in the presence of hydrogen peroxide (H2O2) on the destruction of the cyanobacterium Synechococcus leopoliensis (S. leopoliensis) under irradiation with visible light. Data presented in this paper illustrate that illumination of S. leopoliensis in the presence of a photosensitiser (MB) and H2O2 results in the decomposition of both the cyanobacterium and the photosensitiser. The presence of MB and H2O2 affects the viability of the photosensitiser and the cyanobacterium with the fluorescence of both decreasing by 80% over the irradiation time investigated. The photo-dynamic effect was observed under aerobic and anaerobic conditions indicating that oxygen was not necessary for the process. This novel combination could be effective for the remediation of biofilm colonised stone surfaces

Original languageEnglish
Pages (from-to)63-68
Number of pages6
JournalJournal of Photochemistry and Photobiology B: Biology
Issue number1
Early online date26 Jan 2006
Publication statusPublished - 03 Apr 2006


  • Biofilm
  • Cyanobacteria
  • Hydrogen peroxide
  • Methylene blue
  • Photosensitiser
  • Synechococcus leopoliensis

ASJC Scopus subject areas

  • Plant Science
  • Bioengineering
  • Physical and Theoretical Chemistry

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