The role of physicochemical interactions and FLO genes expression in the immobilization of industrially important yeasts by adhesion

One of the industrially important qualities of yeast is their ability to provide the cell-cell and cell-support interactions. This feature of yeast is responsible for technologically significant phenomena such as flocculation (brewing) and yeast biofilm formation (immobilization to supports), whereas these phenomena are time, environment, and strain dependent. Therefore, the goal of this work was to verify the possibility to predict and subsequently select yeast strains capable to colonize solid supports by using physicochemical adhesion models. Three different industrial yeast strains (Saccharomyces cerevisiae) were tested for their adhesion onto spent grain particles in the continuous gas-lift reactor. The cell adhesion energies were calculated, based on physicochemical characteristics of surfaces involved, according to three adhesion models (DLVO theory, thermodynamic approach, and extended DLVO theory). The role of physicochemical surface properties in the cell-cell and cell-support interactions was evaluated by comparing the computed predictions with experimental results. The best agreement between forecast and observation of the yeast adhesion to spent grains was achieved with the extended DLVO (XDLVO) theory, the most complex adhesion model applied in this study. Despite its relative comprehensiveness, the XDLVO theory does not take into account specific biochemical interactions. Consequently, additional understanding of the yeast adhesion mechanism was obtained by means of quantifying the expression of selected FLO genes. The presented approach provides tools to select the appropriately adhesive yeast strains and match them with solid supports of convenient surface properties in order to design immobilized biocatalysts exploitable in biotechnological processes.