Figure 2.

(A) PCR amplification of the DNA fragments included between a sequence of Tn5 (5′ → 3′ ACTTGTGTATAAGAGTCAG) and different oligonucleotides present in the genome of P. putida U separated by 400–600 bp. Mw, size markers; C, control without oligonucleotides. (B) Analysis of the P₁, P₂, and P₃ promoters. The existence of a functional promoter implies the expression of the lacZ gene present in the plasmid pRS551. Blue color is generated by the hydrolysis of 5-bromo-4-chloro-3-indolyl β-d-galactoside (X-Gal). The upper three patches are E. coli MC4100 transformed with the parental promoter-probe plasmid; the lower three patches are E. coli MC4100 transformed with the recombinant plasmid carrying the indicated promoter.