Extracellular Polymer of Candida albicans: Isolation, Analysis and Role in Adhesion

Abstract

Extracellular polymeric material (EP) was isolated from culture supernatants of C. albicans grown on C sources (50 mM glucose, 500 mM sucrose or 500 mM galactose) known to promote yeast adhesion to different extents. Galactose-grown yeasts, which are the most adherent, produced more EP than sucrose-grown organisms, particularly after incubation for 5 days, while glucose-grown yeasts (the least adherent) gave the lowest yield. EP produced on all 3 C sources was of similar composition and contained carbohydrate (65-82%: mannose with some glucose), protein (7%), P (0.5%) and glucosamine (1.5%). Serological studies indicated that these EP preparations were immunologically identical but that galactose-grown yeasts had more antigenic determinants than sucrose-grown organisms while glucose-grown yeasts had the fewest determinants. Antigenic differences were apparent between EP preparations of some strains of C. albicans. Pretreatment of acrylic strips with EP to form a polymeric coating promoted yeast adhesion to the acrylic surface, but similar pretreatment of buccal epithelial cells with EP inhibited subsequent yeast adhesion. These results indicate that EP originates from the cell surface of C. albicans and that it contains the surface component(s), probably mannoprotein in nature, responsible for yeast adhesion. [The relevance of these findings to oral thrush and to denture stomatitis is discussed.].