The effect of cell type and shape on biomass measurements. As the Biomass Monitor detects intact plasma membranes by using an electric field to induce charge separations across them it can detect any type of cell irrespective of its shape. This point is illustrated for a variety of cell types and shapes in figure 3.4. By measuring the D C of these curves one can measure the biomass content of the suspensions exactly as described previously. The cell wall surrounding many cells has no effect on the b -dispersion and hence on biomass measurement.
Some cell types can occur in chains or clumps.
It has been found experimentally that the walls of bacteria and yeast do not impede the motion of ions up to the cells plasma membranes when an electric field is applied. This has two important consequences. Firstly the b -dispersion is not affected by the presents of the walls. The second is that the b -dispersion of a clump of walled cells is not effected by the clumping because of the walls acting as channels for the ions to move through. The situation for clumps of non-walled cells is more complex but what will probably be found is that the D C of the suspension is slightly less than expected.