Figure 7. Activity and expression level of antioxidant enzymes.

(A–F) Activities of antioxidative enzymes. Bacterial cells grown to stationary phase were exposed to 100 mM H₂O₂, 20 mM formaldehyde, 0.3 mM CdCl₂, 70 mM CDNB, and 375 μg/ml ciprofloxacin for 30 or 60 min at 30 °C. Crude protein extracts were prepared and then used to measure enzyme activity. Each enzyme activity is represented as U/mg of protein. Mean values with standard deviations (error bars) from at least three independent experiments are shown. *P ≤ 0.05. (G) The WT(pXMJ19) and WT(pXMJ19-His₆-mtr) strains grown to mid-log phase were exposed to multiple stressors for 30 min at 30 °C. The levels of indicated gene expression were determined by qRT-PCR. The mRNA levels were presented relative to the value obtained from cells without treatment. The values represent the mean results from three independent cultivations, with standard errors. *P ≤ 0.05. **P ≤ 0.01. CAT, catalase; SOD, superoxide dismutase; MPx, mycothione peroxidase; Mrx1, mycoredoxin 1; MsrA, methionine sulfoxide reductase A; Trx1, thioredoxin 1.