Target construct for recombination-mediated cassette exchange (RMCE) using the Bxb1:int integrase. Contains a Tn\neoRHsp70Bb.PS marker flanked by a pair of inverted 48bp minimal attP(Bxb1) sites. The entire attP(Bxb1)-flanked cassette can be replaced with DNA from a compatible donor plasmid (where the sequence to be inserted is flanked by inverted attB(Bxb1) sites) through RMCE driven by the Bxb1:int integrase. A single loxP site is also present, immediately preceding the RMCE cassette.