FIG 3 .

Certain non-SUSP phages also promote significant plasmid transformation. Data represent the yields of antibiotic-resistant transformants obtained from DNA extracted from lysates in which ~10⁸ E. coli Le392 cells bearing ampicillin resistance plasmid pBAD24 were lysed by phage SUSP2 (squares), λcI⁻ (triangles), T4GT7 (inverted triangles), or wild-type T4 (diamonds). Because known—but slightly varying—numbers of E. coli MG1655 cells were used in different replicates, raw transformant counts were normalized to the per-10⁸-cells-lysed standard. The control represents transformation of plasmid DNA extracted with a commercial kit from the same number of bacterial cells as were lysed by phage. Horizontal lines within each cluster of data points represent the mean values of at least three independent biological replicates. The asterisk denotes statistical significance at a standard of P < 0.05 (Mann-Whitney U test).