Figure 5

The effect of a range of extracellular nucleotide signals on twitching motility-mediated expansion of P. aeruginosa biofilms. Phase-contrast microscopy of interstitial biofilms of P. aeruginosa PAK in the presence of a range of nucleotides after incubation for 15 h at 37°C. (A) Relative expansion distances of P. aeruginosa PAK interstitial biofilms towards a range of saturated discs after incubation for 15 h at 37°C. A value of 1 indicates that P. aeruginosa expanded up to the edge of the saturated disc. The data are represented as the mean ± SD from four independent experiments. (B) Low magnification images of expansion of the interstitial biofilm away from the main colony towards a H₂O, ATP, dATP or CTP-saturated disc (scalebar is 500 μm) and (C) high magnification images of the biofilm edge closest to the disc (scalebar is 50 μm and the arrows indicate the direction of expansion towards the disc). Images are representative of four independent experiments.