| Abstract: | Cell surface hydrophobicity may be an important factor contributing to the virulence of Candida yeast cells. Surface hydrophobic and surface polar groups would be required for a yeast cell to act as a surface-active agent. In this report, the surface activities of whole yeast cells were measured. Yeast cells added at 10(8)/ml reduced the surface tension (gamma s) of saline by 20% as determined by the du Nouy method. A 1% suspension of yeast cell wall fragments reduced gamma s of saline by 36%. Whole yeast cells caused a reduction in interfacial tension (gamma I) between hexadecane and saline. The reduction of gamma I was proportional to the surface hydrophobicity of the yeasts. Yeast cells grown in glucose as the sole carbon source (thus possessing a relatively more hydrophilic cell surface) reduced gamma I by 30%, whereas yeast cells grown in hexadecane (thus possessing a more hydrophobic cell surface) reduced gamma I by 41%. The reduction of gamma I was reversed upon the addition of a strong surfactant. It was also demonstrated that yeast cells blended with nonionic surfactants during growth in a glucose broth in order to change their cell surface hydrophobicity adhered to solid surfaces in direct proportion to their cell surface hydrophobicity. Thus, the surface-active properties of Candida yeast cells may significantly contribute to the accumulation of yeast cells at various biological interfaces such as liquid-solid, liquid-liquid, and liquid-air, leading to their eventual adhesion to solid or tissue surfaces. |
