Fig 1.

Effects of ppGpp deficiency on Shiga toxin-converting phage plaque morphology. Plaques formed by bacteriophages ϕ24B, 933W, P22, P27, and P32 on lawns of E. coli strain MG1655 (wild type [WT]) and its relA spoT derivative (ppGpp⁰), grown in LB, were analyzed. (A) Pictures of plaques were taken using an HP Scanjet G4050 digital scanner. The bar represents 1 cm. (B) Measured sizes of plaques on lawns of E. coli strain MG1655 (WT) (open bars) and its relA spoT derivative (ppGpp⁰) (closed bars). One hundred fifty randomly chosen plaques were measured for each phage titrated on each host, and the percentage of plaques included in each size range was determined. (C) Growth curves of E. coli MG1655 (WT) (open symbols) and its relA spoT derivative (ppGpp⁰) (closed symbols) cultured in LB medium at 37°C. Mean values from 3 experiments are shown (standard deviations [SD] were below 10%, and thus error bars would be smaller than sizes of symbols, especially in the logarithmic scale; therefore, they are not presented).