Fig 5. Intracellular concentrations of seven sigma factors in E. coli K-12 W3110 type-A strain.

E. coli K-12 W3110 type-A strain was grown in LB medium at 37°C with shaking. Cells were harvested at various times and cell lysates were subjected to the quantitative immuno-blot analysis of all seven sigma factors as described in Materials and Methods. [A] The sigma levels at exponential growth phase; [B] the sigma levels in the stationary phase.