FIG. 4.

(A) β-Galactosidase activities of the benA-lacZ fusion (pCCH101) in wild-type (PRS2000) and benR mutant (PRS4157) cells. Cells were grown on succinate (white), succinate plus benzoate (black), or succinate plus catechol (gray) and assayed as described in Materials and Methods. (B) β-Galactosidase activities of E. coli cells harboring the benA-lacZ fusion (pCCH101) and/or the BenR expression construct (pCCH106) in the absence (white) or presence (black) of 1 mM benzoate. β-Galactosidase activity was assayed as described in Materials and Methods.