FIG. 6.

Inactivation of phpA in an algB::Tn501 strain results in increased algD expression. The four strains shown were constructed by replacing the chromosomal wild-type algD with algD::xylE by allelic exchange. XylE activity was assayed as detailed in Materials and Methods. Activity was normalized by dividing by the OD₅₄₀ at the time of harvest. For each experiment, the activity of strain FRD875 was set at 100%. The activities of the remaining strains were then expressed as percentages of the activity of FRD875. The results of six independent experiments were used to determine the means and standard deviations shown.