Central metabolism is a key player in E. coli biofilm stimulation by sub-MIC antibiotics
Fig 6
Differing effects of nitrate on biofilm stimulation across a panel of antibiotics.
Biofilm assays were performed using peg lids in liquid 50:50 media with or without 50 mM potassium nitrate. Each antibiotic (CEF = cefixime, NOVO = novobiocin, TET = tetracycline, CHL = chloramphenicol, AZI = azithromycin, ERM = erythromycin, SPEC = spectinomycin, SOL = solithromycin) was tested across a range of 2x serial dilutions, and the maximum biofilm stimulation (highest average at one concentration) for each condition was plotted as a percent of the untreated control. Percent of control indicates the Biofilm (Abs600) values for treatment by a given condition divided by the Biofilm of the matched vehicle control multiplied by 100. The mean Abs600 raw values are shown above their respective biofilm bar. “30S” and “50S” indicate the target subunit for ribosome inhibiting compounds. “Static” and “Cidal” are shorthand for bacteriostatic and bactericidal, respectively. Fold change was calculated by dividing the maximum biofilm stimulation value of the nitrate treated sample by the no nitrate control value. The data are representative of three biological replicates. A one-way ANOVA followed by Šidák’s multiple comparisons test was performed in GraphPad Prism to compare biofilm formation between the -/+ nitrate wells for each antibiotic (**** = p value <0.0001). Unlabelled columns are non-significant.