Chromosomal insertion of the entire Escherichia coli lactose operon, into two strains of Pseudomonas, using a modified mini-Tn5 delivery system

Gene. 1997 Feb 28;186(2):167-73. doi: 10.1016/s0378-1119(96)00688-9.


A 12-kb PstI fragment including the entire E. coli lactose operon (lacIPOZYA) was inserted in one copy into the chromosome of Pseudomonas putida, Pseudomonas fluorescens and an E. coli strain with lac- phenotype. This was made possible by improvements of an already existing mini-Tn5 transposon delivery system (de Lorenzo et al., 1990; Herrero et al., 1990), which integrates cloned DNA fragments at random sites on the chromosome of the recipient bacteria in single copies. This has resulted in: (a) the making of two useful low copy-number cloning vectors both with extensive multi-cloning regions flanked by NotI sites needed in the mini-Tn5 delivery system; (b) the generation of E. coli nonlysogenic strains expressing the pi protein thus being capable of maintaining and delivering R6K-based mini-Tn5 vectors to other E. coli strains; (c) the successful insertion of the E. coli lactose operon into the P. fluorescens chromosome giving P. fluorescens the ability to grow on lactose; (d) evidence from Southern blotting that contradicts the assumption that the mini-Tn5 delivery system always creates one-copy inserts. These improvements allow insertion of large DNA fragments encoding highly expressed proteins into the chromosome of a large variety of Gram-negative bacteria including E. coli.

MeSH terms

  • Chromosomes, Bacterial
  • DNA Transposable Elements*
  • Escherichia coli / genetics*
  • Genotype
  • Isopropyl Thiogalactoside / pharmacology
  • Kinetics
  • Lac Operon*
  • Mutagenesis, Insertional / methods*
  • Phenotype
  • Plasmids
  • Pseudomonas fluorescens / drug effects
  • Pseudomonas fluorescens / genetics*
  • Pseudomonas fluorescens / growth & development
  • Pseudomonas putida / genetics*
  • Restriction Mapping


  • DNA Transposable Elements
  • Isopropyl Thiogalactoside