title: Persistence of the pBR 322 plasmid in Escherichia coli K 12 grown in chemostat cultures.
abstract: Populations of a Escherichia coli K 12 strain, containing the vector plasmid pBR 322, were grown in chemostat culture under glucose- and phosphate-limited conditions. Resistance to tetracycline and ampicillin were lost after prolonged cultivation, resulting in the production of apparent plasmid-free populations which were more competitive than the original population. This competitiveness between plasmid-free and plasmid-containing populations was greatest in environments where the nutrient restriction was severe. Also during sequential subcultivation in batch cultures loss of plasmid was observed.
mesh_terms: D000667:Ampicillin / Q000494:pharmacology; D003470:Culture Media; D004926:Escherichia coli / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism; D005822:Genetic Vectors; D005947:Glucose / Q000378:metabolism; D010710:Phosphates / Q000378:metabolism; D011815:R Factors; D013752:Tetracycline / Q000494:pharmacology
chemical_list: D003470:Culture Media; D010710:Phosphates; D000667:Ampicillin; D013752:Tetracycline; D005947:Glucose