FIG. 5.

Effect of pH and salt. Bacteria were grown in trypticase-peptone-glycerol, overnight cultures were washed twice by centrifugation as described by Howard and Inglis (25), and the cells in the pellet were resuspended in cold sterile water at the indicated pH or NaCl concentrations. Panel A shows the divergence between B. pseudomallei colony counts and viable cells as detected by flow cytometry and supravital stains produced by incubation at low pHs. Panel B shows the same divergence between culturable cells and viable cells counted by flow cytometry of B. pseudomallei NCTC 13177 at various NaCl concentrations. Open boxes indicate bacterial counts in numbers of CFU/ml. Closed boxes indicate viable bacterial counts as detected by flow cytometry.