title: Influence of pH on the molecular weight of poly-3-hydroxybutyric acid (P3HB) produced by recombinant Escherichia coli.
abstract: The production of ultrahigh molecular weight poly-3-hydroxybutyric acid (P3HB) from carbohydrates by recombinant Escherichia coli harboring genes from Ralstonia eutropha was evaluated. In shaken-flask experiments, E. coli XL1 Blue harboring plasmid pSK::phaCAB produced P3HB corresponding to 40 and 27% of cell dry weight from glucose and xylose, respectively. Cultures in bioreactor using glucose as the sole carbon source at variable pH values (6.0, 6.5, or 7.0) allowed the production of P3HB with molecular weight varying between 2.0 and 2.5 MDa. These figures are significantly higher than the values often obtained by natural bacterial strains (0.5-1.0 MDa). Contrary to reports of other authors, no influence of pH was observed on the molecular weight of the polymer produced. Using xylose, P3HB with high molecular weight was also produced, indicating the possibility to produce these polymers from lignocellulosic materials.
authors.affiliation: Department of Microbiology, Institute of Biomedical Sciences, University of São Paulo, Av. Prof. Lineu Prestes 1374, 05508-900 São Paulo, São Paulo, Brazil.
authors.forename: Johanna Katherine
authors.initials: JK
authors.lastname: Bocanegra
authors.forename: José Geraldo
authors.initials: JG
authors.lastname: da Cruz Pradella
authors.forename: Luiziana Ferreira
authors.initials: LF
authors.lastname: da Silva
authors.forename: Marilda Keico
authors.initials: MK
authors.lastname: Taciro
authors.forename: Jose Gregório Cabrera
authors.initials: JG
authors.lastname: Gomez
mesh_terms: D020118:Cupriavidus necator / Q000502:physiology*; D004926:Escherichia coli / Q000502:physiology*; D006863:Hydrogen-Ion Concentration; D006885:Hydroxybutyrates / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism*; D008970:Molecular Weight; D009097:Multienzyme Complexes / Q000235:genetics / Q000378:metabolism*; D011091:Polyesters / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism*; D000094122:Polyhydroxybutyrates
chemical_list: D006885:Hydroxybutyrates; D009097:Multienzyme Complexes; D011091:Polyesters; D011994:Recombinant Proteins; C003182:poly-beta-hydroxybutyrate; D000094122:Polyhydroxybutyrates