Fig. 1

A Intracellular survival in A. castellanii of adapted (black) and non-adapted (grey) isolates calculated by dividing the CFU at 4 h by the CFU at 2 h of the assay. B Intracellular competitive fitness of adapted isolates in A. castellanii. C In vitro competition assay of adapted isolates grown in LB for 24 h. Competition index (CI) in amoeba (B) and in LB medium (C) was calculated by dividing the output ratio (adapted/?lacZ) after incubation, corrected by the input ratio. Statistical analysis was performed to determine the significance of the CI of days 45 and 90 isolates compared to day 3 isolates. D Swimming motility of the adapted (black) and non-adapted (grey) isolates expressed as diameter (mm) of the zone travelled from point of inoculation by bacteria grown overnight on semi-solid LB agar plates. E Biofilm biomass of adapted (black) and non-adapted (grey) isolates as quantified by crystal violet staining. F Haemolytic activity of adapted (black) and non-adapted (grey) isolates expressed as percent haemolysis of 1% sheep erythrocyte suspension. G Protease activity of cell-free supernatants of adapted (black) and non-adapted (grey) isolates measured by azocasein hydrolysis. Data are obtained from 30 individual adapted and non-adapted isolates from 3 time points (days 3, 45 and 90). Data are shown as the median. Statistical analyses for (A, D, E, F, G) were performed using two-way ANOVA and Sidak?s multiple comparisons test. For (B, C) statistical analyses were performed using one-way ANOVA and Kruskal?Wallis test. Statistical significance is indicated by ^???p < 0.001.