FIG. 2.

RExBAD cassette can modulate gene expression. The histograms show the β-galactosidase activities of strain MG1655ΔlacIZ, strain MG1655catRExBADlacZ, and wild-type strain MG1655 grown to the stationary phase in LB medium (A) and in M63B1 medium containing 0.4% glucose (B). The concentration of the added sugar, either glucose (glu) or arabinose (ara), is indicated under each bar. Ø indicates that no sugar was added. The MG1655ΔlacIZ strain corresponded to a lac-minus control strain, whereas the expression of the lac operon by MG1655 grown in presence of 1 mM IPTG was considered wild-type expression. (Insets) Enlargements of the parts of the graphs related to comparisons of a real lac mutant strain and MG1655catRExBADlacZ under repressing conditions. The experiments were performed in triplicate.