YEASTS ISOLATED FROM THE INTESTINE OF RAINBOW-TROUT ADHERE TO AND GROW IN INTESTINAL MUCUS

The yeast strains Saccharomyces cerevisiae CBS 7764 and Debaryomyces h ansenii Hf1 (CBS 8339), isolated from the intestine of rainbow trout, were studied with respect to adhesion to and growth in fish intestinal mucus. The level of adhesion was dependent on the physiologic state o f the yeast culture. Growing cells of both strains adhered more strong ly than nongrowing cells. This correlates with a previously shown shif t in cell surface hydrophobicity of these yeasts. In addition, forces other than hydrophobic interactions may participate, as all strains te sted adhered more strongly to the membrane lipid phosphatidylserine th an to phosphatidylcholine and phosphatidylethanolamine. Debaryomyces h ansenii Hf1 also adhered to the most hydrophobic of the neutral lipids present in mucus, while no adhesion was observed to the other neutral lipids or to the hydrophilic silica gel, again suggesting hydrophobic interactions. Finally, the fish-isolated yeasts grew rapidly in isola ted fish intestinal mucus as the sole source of energy and nutrients.