Comparison of plate counting and FCM measurements of microbial growth during spaceflight. Wild-type P. aeruginosa was cultured under normal gravity (black bars) and spaceflight (gray bars) conditions in mAUMg containing 5 mM or 50 mM phosphate. (a) The number of viable cells in unfixed samples was measured by plate counting. (b) The number of cells in fixed samples was measured by flow cytometry (FCM). Statistical differences between normal gravity and spaceflight for each experimental condition were analyzed by one-tailed t-test: *p < 0.05. Error bars indicate SD; N = 3.