Physicochemical and biochemical interactions in yeast immobilization by adhesion to a cellulose based support

An important quality of yeast cell wall is the ability to adhere to other cell walls or solid surfaces. This feature of yeast is responsible for technologically important phenomena such as flocculation at the end of beer fermentation and cell adhesion to immobilization supports e.g. spent grains, DEAE-cellulose etc. Physicochemical properties of yeast surfaces, e.g. hydrophobicity and surface charge, have a substantial impact on cell adhesion and flocculation. The interaction energies calculated according to DLVO theory and interfacial free energies were compared with yeast adhesion experiments carried out in continuous gaslift reactor. Four different brewing yeast strains (Saccharomyces cerevisiae) were tested for their adhesion onto spent grain particles. The role of physicochemical surface properties in cell-cell and cell-carrier interactions was evaluated by comparing the computed predictions with experimental results. In view of the somewhat contradictory results, the importance of specific biological interactions is outlined. Preliminary results on the presence of FLO 11 gene in studied yeast stains are presented.