Fig. 5.

Mixed infections reveal social strain dynamics but no successful cheating. a Relative fitness of the wildtype PAO1-mCherry after 42 h of competition inside the C. elegans gut against an untagged PAO1 control strain; the siderophore-negative strain PAO1ΔpvdDΔpchEF; and the Las-negative strain PAO1ΔlasR. The control competition revealed a mild but significant negative effect of the mCherry tag on wildtype fitness. When accounting for these mCherry costs, we found that the putative cheat strains PAO1ΔpvdDΔpchEF and PAO1ΔlasR performed equally well compared to the wildtype, but could not outcompete it. This suggests that virulence factor deficient strains benefit from the presence of non-producers but cannot successfully cheat on them. b At 6 hpe, wildtype frequency in mixed infections correlated positively with total bacterial load inside hosts in competition with PAO1ΔpvdDΔpchEF (diamonds and dotted lines) and PAO1ΔlasR (squares and dashed lines) but not in the control competition (circles and solid lines). These correlations disappeared at 48 hpe. Each data point represents an individual worm. Data shown in a+b stem from the same three independent experiments