Fig. 1. Growth temperature influences biofilm architecture in P. aeruginosa.

a Comparison of the scanning electron microscopy images of Pseudomonas aeruginosa wild-type biofilms grown for 48 h at 23 and 37 °C. Images show ×8000 and ×15,000 magnification and are representative of three independent experiments. b Congo red binding assay. Extracellular matrix production by the wild type was evaluated on tryptone agar plates containing Congo Red and Coomassie brilliant blue G after incubation at 23 and 37 °C for 72 h. Representative images of the colony morphologies of WT PA14 are shown. Scale bar: 5 mm. c Crystal violet staining revealed subtle temperature-dependent architectural differences. d The biomass of the biofilm was higher at 23 °C when compared to 37 °C. Bars represent the mean of three biological replicates performed on different days. The mean of each biological replicate was based on three technical replicates. Error bars represent the standard error of mean of the biological replicates. Unpaired t-test (two-tailed) was used to measure statistical significance. *p = 0.0146.