Figure 7. MamA affects viability in hypoxic conditions.
The indicated strains of H37Rv were normalized to a calculated density of 3×106 CFU/ml and sealed in bottles containing equal volumes of culture and headspace. (A) Two bottles per strain were opened at the indicated timepoints and CFU/ml determined by plating. Error bars denote standard deviation. The negative slopes of the time points between day 14 and day 35 differ significantly between ΔmamA and the other two strains (P<0.05, linear regression of log10-transformed values according to the method in [96]). (B) After 28 days, samples of culture were treated with fluorescein diacetate and visualized by microscopy. Only live cells containing active intracellular esterases cleave fluorescein diacetate to produce fluorescent fluorescein. Scale bar = 10 µm. (C) Quantification of percent fluorescent bacteria in three-four fields at day 28. Error bars denote 95% confidence intervals. P<0.05 for all inter-strain comparisons (Fisher's exact test).