(A) Static biofilm formation of eight targeted gene deletion mutants, compared to attachment of WT SL1344. Following incubation at 25°C for 24 h in CFA medium, the level of biofilm formation is expressed as a percentage of WT SL1344 which had an A590 nm of 0.56 ± 0.04 in this experiment. The ΔtrpE (JH3185) (* P = 0.0001) and ΔSTM0341 (JH3187) (* P = 0.001) mutants showed significantly less attachment to polystyrene than WT SL1344. The mean absorbance values from four wells are shown as a percentage of WT SL1344 and the error bars represent the SD between four technical replicates (n = 3). (B) The attachment of the ΔtrpE (black diamonds) mutant (JH3185) to the bottom surface of a glass flow cell compared with S. Typhimurium SL1344 (back circles). Bacteria were cultured at 25°C in CFA medium in a glass flow cell. Error bars represent the standard deviation between 6 images captured along the length of the flow cell over 24 h (n = 3).