Figure 4

From: Optimised chronic infection models demonstrate that siderophore ‘cheating’ in Pseudomonas aeruginosa is context specific

Figure 4

Relative fitness of ΔpvdD and ΔpvdDΔpchEF mutants in pure culture (grey bars) and in mixed culture with an isogenic wild type (white bars) in SWF after (a) 24 and (b) 48 h of growth. Bars show means of 10 replicates split across two replica experiments, with associated 95% confidence interval. Twenty-four hour fitnss was detemrined only by the presence/absnece of the wild type (ANOVA eliminating experimental block: genotype F1,35=0.621, P=0.436; presence/absence of wild type: F1,35=35.2, P<0.001; interaction term: F1,35=2.82, P=0.102); The ΔpvdD mutant’s relative fitness was not significantly different from 1 in pure culture (post hoc t-test, P=0.051), and the ΔpvdDΔpchEF mutant slightly and significantly >1 (P=0.006), but both were less fit than the wild type in mixed culture (P=0.032 and <0.001, respectively). Forty-eight-hour fitness was not affected by genotype or co-culture (ANOVA eliminating experimental block: genotype: F1,35=0.045, P=0.833; presence/absence of wild type: F1,35=1.34, P=0.255; interaction term: F1,35=0.078, P=0.781): both mutants had a relative fitness of 1 regardless of wild type presence (post hoc t-tests, P0.104). In both panels, results of post hoc tests for relative fitness=1 are shown with *=P<0.02; n.s.=not significant. Confidence intervals and P-values in (b) are taken from a model that excluded two outliers where relative fitness was zero (indicated by open diamonds): including these outliers in the analysis did not change any of the conclusions given in the text.