| abstract |
(57) [Summary] The present invention relates to a nucleic acid construct (1) introduced into a double selection vector (2) capable of transforming a cell (3) of a specific organism, wherein the construct (1) is composed of two different genes. (10 and 11), each gene encoding a different toxic molecule (4 and 5) for prokaryotic cells, preferably E. coli, said genes (10 and 11) being upstream and downstream of the cassette sequence (8); Alternatively, the nucleic acid construct is arranged downstream and upstream of the site for insertion of the cassette sequence (8), and the nucleic acid construct contains specific sequence portions (12, 12 ′) that inactivate the genes (10 and 11). |