The Xer-cise method, like other technologies used to modify bacterial strains for bioproduction, uses DNA cassettes containing antibiotic resistance genes to identify organisms that have successfully integrated the desired gene.
However, unlike these other methods, Xer-cise then allows the antibiotic resistance gene to be removed using a combination of appropriately placed Xer recognition sequences and recombinase enzymes that excise the desired sequence.
This, according to RecipharmCobra, “overcomes the problems caused by the biosafety risk of potentially spreading antibiotic resistance to pathogens, the limited number of available antibiotic resistance genes and the competing use of these genes on plasmids.”
Simon Saxby, VP of Biologics at the firm said: “Xer-cise has enabled molecular biologists at RecipharmCobra and elsewhere to rapidly construct bacterial strains that are not antibiotic resistant, and are therefore advantageous for the commercial production and delivery of biologics.
“We anticipate that this technology will greatly simplify and accelerate the genetic modification of many species of bacteria.”