Figure 3.

Inhibition of cell growth on solid media for wild-type E. coli strain K-12 and the permeable strain AS19 (15). Antiribosomal PNAs and tetracycline were aliquoted by direct pipetting onto overlay cultures before overnight growth. Zones of inhibition are visible at sites of application as clear regions in the lawn of cells. Contrast between zones of clearing and the bacterial lawn was improved by using 5-bromo-4-chloro-3-indoyl β-d-galactoside (X-Gal) media and a red filter for photography.