Oscillations in yeast observed electrically

It has previously been demonstrated that oscillations occur in actively gro wing yeast cultures. These oscillations occur because yeast cells synchroni ze their glycolytic pathway following a saturation period. Periodic changes in the levels of intermediate metabolites in glycolysis as well as, change s in pH of the media have been measured, that demonstrate this phenomenon. Here we observe that the conductivity of the media also changes periodicall y when yeast cells are cultured under similar conditions. As conductivity i s easily measured, this provides a simple, more quantitative method to stud y these changes than those currently used. An electrical biosensor referred to as ECIS (electrical cell surface impedance sensing) was used to study t he small conductivity changes (in the order of 0.1%). No significant differ ences in the observed periods were found in the two yeast strains or the co mmercially purchased yeast extract studied.