FIG. 3.

Expression of hspX in M. smegmatis grown under various stress conditions: Control, the M. smegmatis strain carrying the hspX::lacZ transcriptional fusion plasmid pNChspX was grown aerobically in 7H9-glucose medium to an OD₆₀₀ of 0.5; Hypoxia, the strain was grown in a 250-ml flask filled with 150 ml of 7H9-glucose medium and sealed with a rubber septum on a gyratory shaker (200 rpm) for 15 h following inoculation of the medium with aerobically grown preculture, to an OD₆₀₀ of 0.05; NO and KCN, the strains were initially grown aerobically in 7H9-glucose medium to an OD₆₀₀ of 0.3. The cultures were treated with either 500 μM sodium nitroprusside or 500 μM KCN and further grown aerobically for an additional 2 h. Cell-free crude extracts were used to determine β-galactosidase activity. The β-galactosidase activity is expressed as nanomoles per minute per milligram of protein. All values provided are the average of the results of two independent determinations. Error bars indicate standard deviations.