Figure 7. Influence of temperature on the σ⁵⁴-, and T7-dependent nif systems.

(A) Relative nitrogenase activity of E. coli JM109 strain carrying the σ⁵⁴-dependent nif system at 30°C and 37°C; (B), relative nitrogenase activity of E. coli strains at 30°C (0.2 mM IPTG induction) and 37°C (either 0.005 mM, or 0.2 mM IPTG as indicated); (C), relative nitrogenase activity of E. coli JM109 strain carrying the T7-dependent nif system in response to various IPTG concentrations at 37°C; (D), western blot analysis with antiserum against Fe protein (NifH): WCL (whole cell lysate); Sup (supernatant).