Figure 4

Impact of different culture salt conditions on polystyrene bead (PS) and algal cell impedance. Algal cells were cultured in 0 M, 0.1 M, 0.3 M, 0.7 M, and 1.3 M NaCl amended medium for 1 h. PS beads were used as control and immersed in PBS medium amended with 0 M, 0.1 M, 0.3 M, and 0.7 M NaCl. Both beads and cells were washed and resuspended in PBS before the impedance measurements were made. (a) Average PS bead transparency calculated using peak intensity measured at 20 MHz over peak intensity measured at 500 kHz. (b) Average cell transparency calculated using peak intensity measured at 20 MHz over peak intensity measured at 500 kHz. These results show that the PS bead transparency changed very little in the different salt treatments, whereas algal cell transparency decreased significantly from 0 M to 0.3 M and then increased from 0.3 M to 1.3 M.