INVESTIGATION OF THE VALUE OF BETA-GLUCAN-SPECIFIC FLUOROCHROMES FOR PREDICTING THE BETA-GLUCAN CONTENT OF THE CELL-WALLS OF ZOOPATHOGENIC FUNGI

We have used the fluorescent dyes aniline blue and calcofluor white to stain the cell walls of a variety of pathogenic fungi, and compared our observations with the sensitivity of these species to inhibitors of polysaccharide biosynthesis. Calcofluor white, which interacts with 1,4-beta-glucans such as chitin, chitosan and cellulose, induced fluorescence with all the fungi tested. However, aniline blue, which binds to 1,3-beta-glucans, did not interact with Cryptococcus neoformans, Pityrosporum canis or Rhizopus oryzae. This apparent absence of 1,3-beta-glucan correlates with the insensitivity of these three species to the antifungal echinocandin, an inhibitor of 1,3-beta-glucan synthesis. Thus aniline blue and calcofluor white are useful agents for the study of the presence of beta-glucans in the cell walls of pathogenic fungi.