FIG 5.

Exogenous norspermidine enhances biofilm formation in the wild type, and spermidine reverses this effect. Shown are growth (blue) and biofilm formation (red) with exogenous norspermidine (NSPD) across the indicated concentration range (A) and 200 μM norspermidine plus spermidine (SPD) across the indicated concentration range (B). Values are presented as percentages of the wild type's growth and biofilm formation in the absence of added polyamines (A) and in the presence of 200 μM norspermidine without added spermidine (w/o SPD) (B). Error bars show the standard deviations from a minimum of three biological replicates.