Hyphal formation of Candida albicans is inhibited by salivary mucin

When mucin was added to Candida albicans under hyphal growth conditions, the hyphal formation was inhibited. After the 24 h incubation, the ratio of hyphal cells was 95.7 +/- 1.13% in the absence of mucin and no hyphal cells were observed in the presence of 1000 mu g/ml mucin. The ratio of hyphal cells began to decreases at 6 h in the mucin addition group. Although mucin has antifungal activity, the concentration of mucin used in this assay did not inhibit the growth of C. albicans, indicating that the inhibition of hyphal formation was not due to the inhibition of germination by its antifungal activity. Expression of RAS1mRNA in C. albicans was inhibited by mucin. These results suggest that the inhibition of hyphal formation by mucin was caused by interruption of the hyphal formation signal of C. albicans.