Effect of spaceflight on final cell density of P. aeruginosa . Wild-type P. aeruginosa and a motility mutant (ΔmotABCD) were cultured under normal gravity (black bars) and spaceflight conditions (gray bars) in FPAs with (a) solid inserts or (b) GE inserts. Cells were cultured in mAUM or mAUMg containing 5 mM or 50 mM phosphate. Final cell density was measured by FCM. Effect of phosphate on final cell density is significant in FPAs with solid inserts [two-way ANOVA, ♦♦p < 0.01]. Effect of gravity on final cell density is significant in 5 mM phosphate conditions in FPAs with solid inserts [two-way ANOVA, p < 0.01]. Statistical differences between spaceflight and normal gravity for each experimental condition was analyzed by one-tailed t-test: **p < 0.01; *p < 0.05. Error bars indicate SD; N = 3.