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Article
Photodynamic inactivation of conidia of the fungi Metarhizium anisopliae and Aspergillus nidulans with methylene blue and toluidine blue
Photochemistry and Photobiology
  • Fernanda P. Gonzales
  • Sérgio H. da Silva
  • Donald W. Roberts, Utah State University
  • Gilberto U. L. Braga
Document Type
Article
Publication Date
1-22-2010
DOI
10.1111/j.1751-1097.2009.00689.x
Disciplines
Abstract

Antimicrobial photodynamic treatment (PDT) is a promising method that can be used to control localized mycoses or kill fungi in the environment. A major objective of the current study was to compare the conidial photosensitization of two fungal species (Metarhizium anisopliae and Aspergillus nidulans) with methylene blue (MB) and toluidine blue (TBO) under different incubation and light conditions. Parameters examined were media, photosensitizer (PS) concentration and light source. PDT with MB and TBO resulted in an incomplete inactivation of the conidia of both fungal species. Conidial inactivation reached up to 99.7%, but none of the treatments was sufficient to achieve a 100% fungicidal effect using either MB or TBO. PDT delayed the germination of the surviving conidia. Washing the conidia to remove unbound PS before light exposure drastically reduced the photosensitization of A. nidulans. The reduction was much smaller in M. anisopliae conidia, indicating that the conidia of the two species interact differently with MB and TBO. Conidia of green and yellow M. anisopliae mutants were less affected by PDT than mutants with white and violet conidia. In contrast to what occurred in PBS, photosensitization of M. anisopliae and A. nidulans conidia was not observed when PDT was performed in potato dextrose media.

Citation Information
Gonzales, F.P., S.H. da Silva, D.W. Roberts and G.U.L. Braga. 2010. Photodynamic inactivation of conidia of the fungi Metarhizium anisopliae and Aspergillus nidulans with methylene blue and toluidine blue. Photochemistry and Photobiology 86: 653-661. DOI: 10.1111/j.1751-1097.2009.00689.x.