Colonization of IJ nematodes with TT01 and mutant derivatives. A) Individual IJ nematodes (n = 10), grown on the different bacterial strains (as indicated), were crushed and the lysate was plated on LB agar to enumerate the CFU within the nematode. The data is shown as a boxplot where the horizontal line within the box represents the median value. The box extends to the first and third quartiles and the whiskers show the upper and lower limits of the data (as defined by the statistical test). Asterisks represent outliers. The level of colonization of strains carrying the ΔyfeABCD allele was significantly lower than TT01 (P < 0.0001, Mann-Whitney). B) As above except that the lysate from each crushed IJ was plated on LB agar with or without added 0.1% (w/v) pyruvate, as indicated.