A plasmid is provided comprising the following functional units: a prokaryotic origin of replication, a marker sequence, two specific recombinase recognition sequences and a multiple cloning site, whereby it comprises a gene coding for a sequence specific recombinase, whereby the units are arranged on the plasmid in such a way that the plasmid is divided into a miniplasmid and a minicircle upon expression of the sequence specific recombinase, said miniplasmid comprising the prokaryotic origin of replication, the marker sequence and the gene for the sequence specific recombinase and said minicircle comprising the multiple cloning site.