CONICET | Buscador de Institutos y Recursos Humanos

The surface charge of cells is a physicochemical property associated to the cell envelope composition. In yeasts due to the phosphate groups from the mannosylphosphate residues the net charge is negative. However these charges surrounding the cell could be change as a function of ion exchange driven by the metabolic activity. In this context the aim of this work was to evaluate the capability of zeta potential to sense metabolic or physiological changes on commercial yeast. Taking this in count, assays were performed in order to validate the correlation between cell surface properties and physiological state. Saccharomyces cerevisiae was isolated from instant dry yeast commercial powder and grown in standard medium. Culture samples were collected to evaluate yeast growth, performing CFU, OD600nm and following variations in the electrophoretic mobility of cells in an electric field.In addition the increasing use of selected cultures as starters in many fermentation processes generate the need of finding a method to guarantee efficiency of the inoculum. During several industrial processes, yeast cells are exposed to many types of stresses that induce severe damages to cellular components, resulting in decreased fermentation ability, finally leading to cell death. For this reason the zeta potential was also applied on cells exposed at different kinds of stress. Results were correlated with changes on morphology and surface of yeasts assessed by AFM and fluorescence microscopy.Data obtained show a correlation between the optical density, viability and zeta potential values. Due zeta potential is measured on individual cells, allows a detailed study of cells populations, revealing a coexistence of various subgroups. Moreover, an alteration in the proportions of them could anticipate phase changes. Finally, on stressed cells changes in surface roughness were also related to zeta potential values.

enviar mensaje