FIG. 2.

Expression of lysC, asd, and dapA in different chemically defined media (CDM). Shown is analysis of transcription (closed symbols) of lysC::lacZ (MDW41) (diamonds), asd::lacZ (MDW42) (circles), and dapA::lacZ (MDW43) (triangles). Basal CDM was prepared without the aspartate family amino acids (lysine [Lys], methionine [Met], threonine [Thr], and isoleucine [Ile]). Supplements to 100 mg of Lys and Met per liter and to 150 mg of Thr and Ile per liter were added as follows: a, none; b, Lys, Met, Thr, and Ile; c, Lys; and d, Met, Thr, and Ile. A representative growth curve (MDW41) is shown on each graph (OD₆₀₀ [open squares]). MUG, methylumbelliferyl-β-d-galactoside.