Effect of seven conditions on morphotype switching of type III of 5 B. pseudomallei isolates. (i) TSB culture in air with shaking for 28 h; (ii) intracellular replication in macrophages for 8 h; (iii) exposure to 62.5 μM H2O2 in LB broth for 24 h; (iv) growth in LB broth pH 4.5 for 24 h; (v) exposure to 2 mM NaNO2 in LB broth for 6 h; (vi) exposure to 6.25 μM LL-37 in 1 mM potassium phosphate buffer (PPB) pH 7.4 for 6 h; and (vii) re-exposure to air after incubation in anaerobic chamber for 2 weeks. All experiments were performed using the experimental details described above. B. pseudomallei morphotype on Ashdown agar following incubation in air at 37°C for 4 days was defined and compared with the starting morphotype. Morphotype switching was presented as the proportion (%) of alternative types in relation to the total colonies present.