FIG 3.

Regulatory capacities of the inducible expression systems. (A) Dose-dependent expression of pSSTete2-lacZ. S. suis cells harboring pSSTete2-lacZ plasmid were grown to the mid-log phase and induced with a range of different ATc concentrations for 70 min at 37°C. The cells were harvested, and the β-galactosidase activity was determined as described in Materials and Methods. The data are presented as the mean ± standard deviation. (B) Time-dependent expression of pSSTete2-lacZ. S. suis cells harboring pSSTete2-lacZ plasmid were grown to the mid-log phase and induced for different times in the presence of 150 ng/mL ATc at 37°C. The cells were harvested, and the β-galactosidase activity was determined as described in Materials and Methods. The data are presented as the mean ± standard deviation. (C) Dose-dependent expression of pSSlace1-lacZ. S. suis cells harboring pSSlace1-lacZ plasmid were grown to the mid-log phase and induced with a range of different IPTG concentrations for 70 min at 37°C. The cells were harvested, and the β-galactosidase activity was determined as described in Materials and Methods. The data are presented as the mean ± standard deviation. (D) Time-dependent expression of pSSlace1-lacZ. S. suis cells harboring pSSlace1-lacZ plasmid were grown to the mid-log phase and induced for different times in the presence of 100 μM/mL IPTG at 37°C. The cells were harvested, and the β-galactosidase activity was determined as described in Materials and Methods. The data are presented as the mean ± standard deviation.