title: Metabolic engineering of Escherichia coli for enhanced arginine biosynthesis.
abstract: BACKGROUND
  Arginine is a high-value product, especially for the pharmaceutical industry. Growing demand for environmental-friendly and traceable products have stressed the need for microbial production of this amino acid. Therefore, the aim of this study was to improve arginine production in Escherichia coli by metabolic engineering and to establish a fermentation process in 1-L bioreactor scale to evaluate the different mutants.
  
  
  RESULTS
  Firstly, argR (encoding an arginine responsive repressor protein), speC, speF (encoding ornithine decarboxylases) and adiA (encoding an arginine decarboxylase) were knocked out and the feedback-resistant argA214 or argA215 were introduced into the strain. Three glutamate independent mutants were assessed in bioreactors. Unlike the parent strain, which did not excrete any arginine during glucose fermentation, the constructs produced between 1.94 and 3.03 g/L arginine. Next, wild type argA was deleted and the gene copy number of argA214 was raised, resulting in a slight increase in arginine production (4.11 g/L) but causing most of the carbon flow to be redirected toward acetate. The V216A mutation in argP (transcriptional regulator of argO, which encodes for an arginine exporter) was identified as a potential candidate for improved arginine production. The combination of multicopy of argP216 or argO and argA214 led to nearly 2-fold and 3-fold increase in arginine production, respectively, and a reduction of acetate formation.
  
  
  CONCLUSIONS
  In this study, E. coli was successfully engineered for enhanced arginine production. The ∆adiA, ∆speC, ∆speF, ∆argR, ∆argA mutant with high gene copy number of argA214 and argO produced 11.64 g/L of arginine in batch fermentation, thereby demonstrating the potential of E. coli as an industrial producer of arginine.
authors.affiliation: Biochemical Process Engineering, Division of Chemical Engineering, Department of Civil, Environmental and Natural Resources Engineering, Luleå University of Technology, SE-971 87, Luleå, Sweden. mireille.ginesy@ltu.se.
authors.forename: Mireille
authors.initials: M
authors.lastname: Ginesy
authors.affiliation: Department of Molecular Biosciences Wenner-Gren institute, Stockholm University, SE-106 91, Stockholm, Sweden. jaroslav.belotserkovsky@su.se.
authors.forename: Jaroslav
authors.initials: J
authors.lastname: Belotserkovsky
authors.affiliation: Biochemical Process Engineering, Division of Chemical Engineering, Department of Civil, Environmental and Natural Resources Engineering, Luleå University of Technology, SE-971 87, Luleå, Sweden. josefine.enman@ltu.se.
authors.forename: Josefine
authors.initials: J
authors.lastname: Enman
authors.affiliation: Department of Molecular Biosciences Wenner-Gren institute, Stockholm University, SE-106 91, Stockholm, Sweden. leif.isaksson@su.se.
authors.forename: Leif
authors.initials: L
authors.lastname: Isaksson
authors.affiliation: Biochemical Process Engineering, Division of Chemical Engineering, Department of Civil, Environmental and Natural Resources Engineering, Luleå University of Technology, SE-971 87, Luleå, Sweden. ulrika.rova@ltu.se.
authors.forename: Ulrika
authors.initials: U
authors.lastname: Rova
mesh_terms: D001120:Arginine / Q000096:biosynthesis*; D002262:Carboxy-Lyases / Q000235:genetics / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000235:genetics* / Q000378:metabolism; D055786:Gene Knockout Techniques; D018698:Glutamic Acid / Q000378:metabolism; D060847:Metabolic Engineering; D009955:Ornithine Decarboxylase / Q000235:genetics / Q000378:metabolism; D010957:Plasmids / Q000235:genetics / Q000378:metabolism
chemical_list: D029968:Escherichia coli Proteins; D018698:Glutamic Acid; D001120:Arginine; D002262:Carboxy-Lyases; D009955:Ornithine Decarboxylase; C019722:arginine decarboxylase