1. Two classes of cell pressure responses in cells treated with ampicillin.
Two classes of cell pressure responses in cells treated with ampicillin. Ancylobacter aquaticus cells were examined in a light-scattering apparatus exposed to a range of pressures that at some point crushed their gas-filled vesicles. Without ampicillin treatment, the collapse curve was monophasic like that marked “with sucrose” but required a higher pressure for collapse. After 20 min of treatment, the curve changed to the one marked “without sucrose.” This shows two branches, one higher and one lower than the original curve. The conclusion to be drawn is that different cells in the population exhibited different behaviors. Most of the cells ruptured, and the gas vesicles were exposed to the growth medium and were no longer compressed by the cell's turgor pressure. A smaller number of cells apparently stopped growing and acquired a higher turgor pressure. These cells were immune to the action of the antibiotic because the wall was not growing. (Modified from reference 47.)‏
Arthur L. Koch Clin. Microbiol. Rev. 2003; doi: /CMR