Figure 2. Effect of pH on the H₂ production rate of W3110, ΔhybC, and ΔhycE.

Anaerobic cultures were grown to log phase at pH 5.5 (black bars), 6 (hatched bars), and 6.5 (white bars) and assayed for H₂ production as described in the Materials and Methods. H₂ production rate was calculated as stated in the Materials and Methods. Error bars represent SEM, n = 3; those that were too small to see clearly were omitted. The experiment was conducted twice.