Fig. 2

Evolutionary adaptation of P. aeruginosa to NAg, ionic silver (Ag⁺) and gentamicin (GM) through serial passaging. A A schematic of the passaging experiment. Starting at the respective sub-MIC levels of each agent, the biofilm-forming bacterium was continuously exposed to progressively increasing concentrations of NAg, Ag⁺ and GM for 30 d via sub-culturing every 24 h. The passaging experiment also included a cell-only passaged culture (no antibacterial agent). B The increasing shifts in the highest dosage of NAg, Ag⁺ and GM at which the bacterium could proliferate, with the table detailing the shifts as MIC fold-increase for each agent. Two biological replicates were performed for the passaging experiments, each with three technical replicates. Refer to Additional file 1: Figure S1 for the second biological replicate data