Mediated electrochemical detection of electron transfer from the outer surface of the cell wall of Saccharomyces cerevisiae

Catabolic electron transport processes in yeast are generally considered to be restricted to respiration, glycolysis and trans plasma membrane electron transport (tPMET) proteins. These processes are shielded from the external environment by the cell membrane and a thick cell wall. It has been recently proposed that electrons might be transferred directly from the yeast cell to electrodes. Here we provide the first experimental evidence for electron transfer from the external surface of a yeast cell to an electrode. The electrode has a stable mediator layer that is significantly thinner than the cell wall and unable to make direct contact with any known yeast redox centres. Current measured at the modified electrode in the presence of Saccharomyces cerevisiae is shown to originate both from exported soluble redox species and directly from the external surface of the cell wall. (C) 2011 Elsevier B.V. All rights reserved.