Effect of high density cultivation on plasmid copy number in recombinantEscherichia coli cells

Abstract

The copy number of plasmid harboringE. coli K 12 strains was examined in fed batch cultivations in semisynthetic and synthetic media. Under conditions of high cell density (45–50 g dry weight/I) the plasmid copy number reached a maximum level between 200 and 400 copies per cell. A decrease of phosphate concentration in the medium was obtained similar to the increase of copy number. A high segregational and structural stability of vectors used in this work was observed.