title: Poly(3-hydroxybutyrate) synthesis by recombinant Escherichia coli arcA mutants in microaerobiosis.
abstract: We assessed the effects of different arcA mutations on poly(3-hydroxybutyrate) (PHB) synthesis in recombinant Escherichia coli strains carrying the pha synthesis genes from Azotobacter sp. strain FA8. The arcA mutations used were an internal deletion and the arcA2 allele, a leaky mutation for some of the characteristics of the Arc phenotype which confers high respiratory capacity. PHB synthesis was not detected in the wild-type strain in shaken flask cultures under low-oxygen conditions, while ArcA mutants gave rise to polymer accumulation of up to 24% of their cell dry weight. When grown under microaerobic conditions in a bioreactor, the arcA deletion mutant reached a PHB content of 27% +/- 2%. Under the same conditions, higher biomass and PHB concentrations were observed for the strain bearing the arcA2 allele, resulting in a PHB content of 35% +/- 3%. This strain grew in a simple medium at a specific growth rate of 0.69 +/- 0.07 h(-1), whereas the deletion mutant needed several nutritional additives and showed a specific growth rate of 0.56 +/- 0.06 h(-1). The results presented here suggest that arcA mutations could play a role in heterologous PHB synthesis in microaerobiosis.
authors.affiliation: Departamento de Química Biológica. Facultad de Ciencias Exactas y Naturales, Ciudad Universitaria-Pabellón 2, 1428 Buenos Aires, Argentina.
authors.forename: Pablo I
authors.initials: PI
authors.lastname: Nikel
authors.forename: M Julia
authors.initials: MJ
authors.lastname: Pettinari
authors.forename: Miguel A
authors.initials: MA
authors.lastname: Galvagno
authors.forename: Beatriz S
authors.initials: BS
authors.lastname: Méndez
mesh_terms: D000332:Aerobiosis; D001425:Bacterial Outer Membrane Proteins / Q000235:genetics*; D018533:Biomass; D003470:Culture Media; D004926:Escherichia coli / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000235:genetics* / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D006885:Hydroxybutyrates / Q000378:metabolism*; D009154:Mutation; D011091:Polyesters / Q000378:metabolism*; D011995:Recombination, Genetic; D012097:Repressor Proteins / Q000235:genetics*; D000094122:Polyhydroxybutyrates
chemical_list: D001425:Bacterial Outer Membrane Proteins; D003470:Culture Media; D029968:Escherichia coli Proteins; D006885:Hydroxybutyrates; D011091:Polyesters; D012097:Repressor Proteins; C041610:arcA protein, E coli; C003182:poly-beta-hydroxybutyrate; D000094122:Polyhydroxybutyrates