Cell surface hydrophobicity and its relation to adhesion of yeasts isolated from fish gut

Five different yeast strains isolated from fish, Saccharomyces cerevisiae HF1 and F2, Sc182 (unidentified strain), Rhodotorula rubra and Rhodotorula glutinis , were used in this study. The cell surface hydrophobicity (CSH) was dependent on growth in all cases. Exponential-phase cells were always hydrophobic while stationary-phase cells became hydrophilic. In contrast, two laboratory strains, Saccharomyces cerevisiae Y41 and Debaryomyces hansenii J26 behaved in the opposite manner as previously reported for S. cerevisiae and Candida albicans . This fact, together with microscopic observations, prompts the suggestion that the cessation of population growth (budding) leads to hydrophilic cell differentiation. Irrespective of the degree of hydrophobicity of the surface examined, exponential-phase cells did adhere to a greater extent than stationary-phase cells. These results suggest that hydrophobicity plays an important role in vivo. Since hydrophobic interactions have been suggested to be the most important forces mediating attachment in the aquatic environment, we do believe that these forces mediate the initial events of fish colonization by yeast strains.