Figure 5. The susceptibility to peptide pheromone is transient and optimal at low bacterial densities.

A). Effect of bacterial optical density (O.D. 600 nm) on competence development using a concentration of 10 µg/ml of plasmid DNA (pNZ8048). Competence was not induced over a range of OD values up to 0.3, suggesting that waves of competence do not occur. B). Kinetics of competence induction with plasmid DNA added at the indicated times after ComS13-21 followed 5 min later by addition of DNase (100 U/ml) to degrade any remaining extracellular donor DNA. Error bars show the standard deviation of 4 different experiments.