Immobilization of Saccharomyces cerevisiae by adhesion: Treatment of the cells by Al ions

Abstract

The adsorption of aluminum ions by Saccharomyces cerevisiae has been investigated by determining adsorption isotherms and electrophoretic mobility. The adsorption of aluminum ensures a neutralization of the cell surface charge and allows adhesion of the cells to glass and polycarbonate. Glass slides have been taken as a negatively charged model support, allowing the authors to study in detail the process of adhesion. The cells are simply pretreated by an aluminum solution near pH 4. Bringing the Al-pretreated cells in contact with the support by sedimentation and washing the support and sediment makes it possible to obtain a single, dense, regular layer of cells adhering strongly to the support. Adhesion can also be obtained from a suspension flowing parallel to a vertical support, provided the flow velocity is sufficiently small; the amount of cells immobilized per unit support area is about one-half that obtained by sedimentation. The immobilized cells show a specific activity for ethanol production from glucose which is similar to cells in suspension.