Micromanipulation measurement of the mechanical properties of baker's yeast cells

The mechanical properties of a sample of baker's yeast cells were measured by micromanipulation. The relationship between the force required to burst a single cell and its corresponding diameter was established. For stationary phase cells, the compressive force required to burst a cell varied between 55 and 175 mu N, with a mean value of 101 +/- 2 mu N. This is a substantial force compared to that required to burst a single mammalian cell (1.5-4.5 mu N), which presumably reflects the lack of a cell wall of the latter. From measurements on 120 cells, there was no significant dependence of bursting force on yeast cell size. The micromanipulation method will be valuable for studying the dependence of mechanical properties of yeast cells on fermentation conditions, and the consequential effects of their behaviour in process disruption operations.