Operon containing Exo, Bet, and Gam. To use the lambda red recombineering system to modify your target DNA (including E. coli genome), electroporate a linear donor DNA substrate (either dsDNA or ssDNA) into E. coli expressing the lambda red enzymes. These enzymes then catalyze the homologous recombination of the substrate with the target DNA sequence (mutagenesis uccurs in vivo). ~50 nucleotides of homology are required to the target site for recombination.