FIG. 1.

Effect of spermidine on exponential growth following a shift from 37 to 7°C. The various cultures were grown in LB medium at 37°C to an optical density at 420 nm of ca. 0.5 followed by a shift to 7°C. Where indicated, various concentrations of spermidine were added at the time of the shift. Time zero represents the time of the shift to 7°C. Strains were transformed with pMWSAT (9), the speG⁺ multicopy plasmid, or the vector pMW119 (36).