Figure 4. IPTG induces RpoS and OspC expression.

A total of six 5.0-ml aliquots of ΔrpoS/rpoS_in spirochetes at a density of 10⁴ cells/ml were prepared, supplemented with IPTG to final concentrations at of 0, 0.004, 0.008, 0.016, 0.032 and 0.063 mM, and induced for 8 days. ΔrpoS and ΔrpoS/rpoS cells were used as controls. Bacteria were harvested and analyzed using immunoblotting probed with a mixture of anti-FlaB, OspA and OspC antibodies (upper panel), and RpoS antibody alone (lower panel), respectively.