Figure 2.—

Effect of β-lactamase genes on culture viability. The number of colony-forming units per milliliter is indicative of culture viability. Data for E. coli K12 XL1-Blue containing the indicated plasmids were normalized to E. coli K12 XL1-Blue harboring isogenic plasmid without a β-lactamase gene. Two genetic contexts (pTP123 parent and pUC18-Kn parent plasmids) were examined. Error bars represent the standard deviation of at least six independent experiments. Significance is based on t-test against empty vector: ***P < 0.001.