Despite the abundance of genetic manipulation approaches, particularly for Escherichia coli, new techniques and
increased flexibility in the application of existing techniques are required to address novel aims. The most widely
used approaches for chromosomeediting are based on bacteriophage site-specific andλRed/RecET-mediated homologous
recombination. In the present study, these techniqueswere combined to develop a novel approach for
in vivo cloning and targeted long-length chromosomal insertion. This approach permits direct λRed-mediated
cloning of DNA fragment with lengths of 10 kb or greater from the E. coli chromosome into the plasmid vector
pGL2, which carries the ori of pSC101, the ϕ80-attP site of ϕ80 phage, and an excisable CmR marker bracketed
by λ-attL/attR sites. In pGL2-based recombinant plasmids, the origin of replication can be eliminated in vitro
via hydrolysis by SceI endonuclease and recircularization by DNA ligase. The resulting ori-less circular recombinant
DNA can be used for targeted insertion of the cloned sequence into the chromosome at a selected site via
ϕ80 phage-specific integrase-mediated recombination using the Dual-In/Out approach (Minaeva et al., 2008).
At the final stage of chromosomal editing, the CmR-marker can be excised from the chromosome due to expression
of the λint/xis genes. Notably, the desired fragment can be inserted as multiple copies in the chromosome by
combining insertions at different sites in one strain using the P1 general transduction technique (Moore, 2011).
The developed approach is useful for the construction of plasmidless, markerless recombinant strains for fundamental
and industrial purposes