Construction and molecular cloning of hybrid plasmids containing specific fragments of Escherichia coli DNA

: In the paper a convenient procedure for the isolation of specific Eco RI-fragments of E. coli genome and their amplification on Km-resistance plasmid vector CKdelta11 is described. Plasmid CKdelta11 contains Col E1 replicon and has only one Eco RI site. The hybrid molecules were constructed in vitro using Eco RI-digestion followed by ligation. Then appropriated E. coli strain (polyauxotrophic strain E. coli K12 AB 2463) was transformed with ligated DNA mixture and hybrid plasmids, containing arg, leu, his and thr chromosomal markers were selected by molecular cloning and isolated from the obtained E. coli clones. The hybrid plasmids have two Eco RI sites and consist of one Eco RI-fragment of initial plasmid CKdelta11 and one Eco RI-fragment of El coli DNA. The method described allows to isolate and amplify on hybrid plasmids DNA fragments, containing any selectable genes or genes adjacent to the selectable ones.