Figure 1.

Growth behavior of E. coli hemN and hemW mutants. A, E. coli hemW does not encode a coproporphyrinogen III dehydrogenase. Cells were grown anaerobically at 37 °C in LB medium containing 10 mm NaNO₃ and no antibiotics in tightly sealed anaerobic flasks. Changes in optical density at A₅₇₈ were followed spectroscopically. Values for each strain are averages of three independent experiments with three parallel cultures. The growth of wildtype BW25113 (red), E. coli ΔhemN (green), ΔhemN with pET-3a-hemN (E. coli hemN) (orange), ΔhemN with pGEXhemWF25C (blue), and ΔhemN with pGEXhemWF25C+46N-term (purple) were compared. B, slight growth phenotype of the E. coli hemW mutant. The anaerobic growth in M9 minimal medium supplemented with 5 mm KNO₃ and glycerol as non-fermentable carbon source was compared. Without KNO₃, almost no growth was observed. Growth with KNO₃ of wildtype E. coli BW25113 (red solid line) and E. coli JW2922 (ΔhemW) (blue solid line) and growth without KNO₃ of E. coli BW25113 (red dashed line) and E. coli JW2922 (ΔhemW) (blue dashed line) were compared. Changes in optical density at A₅₇₈ were followed spectroscopically. Values for each strain are averages of six independent experiments with three parallel cultures. Error bars represent S.D.