title: Enhanced plasmid DNA production by enzyme-controlled glucose release and an engineered Escherichia coli.
abstract: OBJECTIVE
  To evaluate the combination of a culture medium employing glucoamylase-mediated glucose reléase from a gluco-polysaccharide and an E. coli strain engineered in its glucose transport system for improving plasmid DNA (pDNA) production.
  
  
  RESULTS
  The production of pDNA was tested using E. coli DH5α grown in shake-flasks and the recently developed VH33 Δ(recA deoR)-engineered strain, which utilizes glucose more efficiently than wild type strains. Three glucoamylase concentrations for releasing glucose from the polysaccharide carbon source were used: 1, 2 and 3 U l(-1). Both strains reached similar cell densities ranging from 5 to 8.8 g l(-1) under the different conditions. The highest pDNA yields on biomass (YpDNA/X) for both strains were obtained when 3 U enzyme l(-1)were used. Under these conditions, 35 ± 3 mgof pDNA l(-1) were produced by DH5α after 24 h of culture. Under the same conditions, the engineered strain produced 66 ± 1 mgpDNAl(-1) after 20 h. pDNA supercoiled fractionswere close to 80 % for both strains.
  
  
  CONCLUSIONS
  The pDNA concentration achieved by the engineered E. coli was 89 % higher than that of DH5α. The combination of the engineered strain and enzyme-controlled glucose release is an attractive alternative for pDNA production in shake-flasks.
authors.affiliation: Plan de estudios en Ingeniería Biológica, Universidad Autónoma Metropolitana-Cuajimalpa, México, DF, Mexico.
authors.forename: Elisa A
authors.initials: EA
authors.lastname: Ramírez
authors.affiliation: Plan de estudios en Ingeniería Biológica, Universidad Autónoma Metropolitana-Cuajimalpa, México, DF, Mexico.
authors.forename: Daniela
authors.initials: D
authors.lastname: Velázquez
authors.affiliation: Departamento de Procesos y Tecnología, Universidad Autónoma Metropolitana-Cuajimalpa, Av. Vasco de Quiroga 4871, Col. Santa Fe, 05348, México, DF, Mexico. alara@correo.cua.uam.mx.
authors.forename: Alvaro R
authors.initials: AR
authors.lastname: Lara
mesh_terms: D061249:Batch Cell Culture Techniques; D004926:Escherichia coli / Q000235:genetics / Q000254:growth & development*; D029968:Escherichia coli Proteins / Q000235:genetics; D005947:Glucose / Q000378:metabolism*; D060847:Metabolic Engineering; D009154:Mutation; D010957:Plasmids / Q000235:genetics*; D019444:Vaccines, DNA / Q000096:biosynthesis
chemical_list: D029968:Escherichia coli Proteins; D019444:Vaccines, DNA; D005947:Glucose
keywords: Galactose permease; Glucoamylase (for glucose release); Glucose release; Metabolic engineering; pDNA vaccines