FIG. 2.

Linear transformation promoted by λ Red is IPTG dependent. Wild-type cells (W3110) containing λ Red-Gam-producing plasmid (pTP223) were incubated for various times in the presence of 1 mM IPTG prior to collection of the cells by centrifugation. Cells were made competent and transformed with equimolar amounts of lacZ::kan fragment (0.12 μg) and parent plasmid pKM131 (0.3 μg). Ratios of transformation titers (fragment/plasmid) were plotted as a function of time of exposure to IPTG.