PCR analysis of marked and unmarked P. aeruginosa PA1520 deletion strains. Colony PCR was performed on either wild-type PAO1 and its PA1520 mutant derivatives, either containing a marked (PA1520::FRT-Gm-FRT) or unmarked (PA1520::FRT) PA1520 deletion. The sizes of the expected PCR fragments are indicated. Note that the short deletion removes 41 bp of the PA1520 coding sequence, corresponding to codons 131 to 145, but replaces these sequences with a 85 bp FRT scar. Lane M contained Hi-Lo molecular size markers of the indicated sizes from Minnesota Molecular.
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