Fig. 1.

β-galactosidase release assay. Cell lysis of planktonic cultures of UAMS-1 (circles) and KB1050 (cidA mutant; triangles), each harboring pAJ22, was monitored by measuring the release of β-galactosidase into the culture supernatant (solid black lines), and its activity was quantified by incubation with o-nitrophenyl-β-d-galactopyranoside and reported in Miller units (70). The growth curves of each strain are also indicated (dashed gray lines). These results represent the average of two independent experiments.