Mannitol prevents the formation of persister cells in <i>P. aeruginosa</i> biofilms.

<p>(A) Biofilms were grown in multiwell plates for 5 h in M9 minimal medium with glucose as a carbon source, with or without mannitol at 5-40 mM. Tobramycin was then added to the culture medium to 80 mg/L and the plates were incubated for a further 2 h before enumerating CFU. Error bars indicate SEM (n = 3). (B) To check for substrate or osmotic effect, mannitol was replaced with NaCl or additional glucose at various concentrations. Error bars indicate SD (n = 4). Asterisks indicate statistically significant difference of combination treatments versus tobramycin only (*, <i>P</i> < 0.05; ***, <i>P</i> < 0.001).