title: Modified Escherichia coli B (BL21), a superior producer of plasmid DNA compared with Escherichia coli K (DH5alpha).
abstract: Plasmid DNA (pDNA) is an emerging experimental vaccine, produced in E. coli, initially targeted for viral diseases. Unlike traditional protein vaccines whose average dose is micrograms, the average dose of pDNA is on the scale of milligrams. Production yields are, therefore, important for the future development of this vaccine. The E. coli strains currently used for pDNA production, JM109 and DH5alpha, are both suitable for production of stable pDNA due to the deletion of recA and endA, however, these two E. coli K strains are sensitive to growth conditions such as high glucose concentration. On the other hand E. coli BL21 is less sensitive to growth conditions than E. coli JM109 or DH5alpha, this strain grows to higher densities and due to its active glyoxylate shunt and anaplerotic pathways is not sensitive to high glucose concentration. This strain is used for recombinant protein production but not for pDNA production because of its inability to produce stable pDNA. To adapt E. coli BL21 for stable pDNA production, the strain was mutated by deleting both recA and endA, and a proper growth and production strategy was developed. Production values, reaching 2 g/L were obtained using glucose as a carbon source. The produced plasmid, which was constructed for HIV clinical study, was found to have identical properties to the plasmid currently produced by E. coli DH5alpha.
authors.affiliation: Biotechnology Core Laboratory, NIDDK NIH Bethesda, Bldg 14A Room 173, Maryland 20892, USA.
authors.forename: Je-Nie
authors.initials: JN
authors.lastname: Phue
authors.forename: Sang Jun
authors.initials: SJ
authors.lastname: Lee
authors.forename: Loc
authors.initials: L
authors.lastname: Trinh
authors.forename: Joseph
authors.initials: J
authors.lastname: Shiloach
mesh_terms: D016915:AIDS Vaccines / Q000096:biosynthesis; D001426:Bacterial Proteins / Q000235:genetics; D004269:DNA, Bacterial / Q000096:biosynthesis*; D004706:Endodeoxyribonucleases / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000235:genetics; D017353:Gene Deletion; D005947:Glucose / Q000378:metabolism; D008565:Membrane Proteins / Q000235:genetics; D010957:Plasmids / Q000096:biosynthesis*; D011938:Rec A Recombinases / Q000235:genetics; D019444:Vaccines, DNA / Q000096:biosynthesis
chemical_list: D016915:AIDS Vaccines; D001426:Bacterial Proteins; D004269:DNA, Bacterial; D029968:Escherichia coli Proteins; D008565:Membrane Proteins; D019444:Vaccines, DNA; D011938:Rec A Recombinases; D004706:Endodeoxyribonucleases; C064668:endA protein, bacteria; D005947:Glucose