title: Ammonium-mediated reduction of plasmid copy number and recombinant gene expression in Escherichia coli.
abstract: The effect of ammonium as a medium supplement on plasmid-encoded recombinant beta-galactosidase synthesis was explored in Escherichia coli cells during aerobic growth in complex medium. After induction, only doses of ammonium chloride below 1 g/L are able to transiently enhance the yield. However, the presence of nontoxic ammonium chloride concentrations of up to 10 g/L results in lower values of beta-galactosidase in a concentration-dependent fashion. A significant reduction in plasmid DNA content explains the decrease in the yield by a gene-dosage-involving mechanism.
authors.affiliation: Institut de Biologia Fonamental, Universitat Autònoma de Barcelona, Bellaterra, Spain.
authors.forename: P
authors.initials: P
authors.lastname: Vila
authors.forename: J L
authors.initials: JL
authors.lastname: Corchero
authors.forename: A
authors.initials: A
authors.lastname: Benito
authors.forename: A
authors.initials: A
authors.lastname: Villaverde
mesh_terms: D000643:Ammonium Chloride / Q000494:pharmacology*; D001483:Base Sequence; D003470:Culture Media; D004790:Enzyme Induction; D004926:Escherichia coli / Q000187:drug effects* / Q000235:genetics* / Q000254:growth & development; D018628:Gene Dosage; D015870:Gene Expression / Q000187:drug effects; D008969:Molecular Sequence Data; D010957:Plasmids / Q000187:drug effects* / Q000235:genetics*; D011995:Recombination, Genetic / Q000187:drug effects*; D001616:beta-Galactosidase / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism
chemical_list: D003470:Culture Media; D000643:Ammonium Chloride; D001616:beta-Galactosidase