FIG. 4.
Quantitative analysis of the total DNA content within the pellets (⧫) and the supernatants (◊) of E. coli NM522 harboring either pML1 plus pSNUC1 (a, b) or only pML1 (c). The data are presented in nanograms of DNA per milliliter of culture taken at various time points during the production of ghosts. The time points of sampling are given in minutes relative to the induction of lysis (0 min). The quantitative results were obtained via real-time PCR with regard to amplification of either the ampr gene (a) or the kanr gene (b, c) encoded by pSNUC1 and pML1, respectively. For practical reasons, the DNA concentrations that fell below the detection limits (grey lines; d.l.) are illustrated as corresponding to the limits of detection, although they do not refer to certain concentrations. The time points of supplementation with IPTG and Mg and Ca and the temperature upshift to 42°C are indicated by arrows.