FIG. 7.

Absence of induction at low concentrations of caffeate or ferulate in strain ADP8116, with a block in HcaB, the aldehyde dehydrogenase. Cultures were grown on succinate with the addition of compounds as noted. ADP8116 cells grown in the presence of 1 mM vanillin, a catabolite of ferulate, had LacZ levels close to those grown on succinate alone (data not shown). Promoter activity was measured, and the averages of three independent trials are shown with their standard deviations.