Fig. 2.

Phenazine-mediated protection does not require matrix or major efflux pumps but depends on carbon source. a Overview of known effects of phenazines on bacterial physiology. Phenazines can inhibit matrix production and induce expression of efflux pumps. Also, phenazines can alter flux through central metabolism and oxidize the cellular redox state. b Quantification of ciprofloxacin tolerance observed for cells from biofilms representing various genetic or environmental conditions. The data for the parent strains (WT and ∆phz) grown with glucose as the carbon source are shown in gray in the left panel. Colored plots show the indicated mutant strains (green, red) or growth on succinate (blue). Each data point (N) is a biological replicate. p values are based on unpaired one-sided t-tests (n.s., not significant; **p ≤ 0.01; ***p ≤ 0.001). ∆pel corresponds to ∆pelB-G, ∆mex to the triple mutant ∆mexGHI-opmD ∆mexVW ∆mexPQ-opmE (see table S1). The center line of the boxplot shows the median, the lower and upper hinges correspond to the first and third quartiles, and the whiskers extend to the most extreme points, limited to 1.5 times the interquartile range