title: On the heterogeneous composition of bacterial polyhydroxyalkanoate terpolymers.
abstract: Poly(3-hydroxybutyrate-4-hydroxybutyrate-3-hydroxyvalerate) (P(3HB-4HB-3HV)) terpolymers of low 3-hydroxyvalerate (3HV) content (1.7-6.4%) with 4-hydroxybutyrate (4HB) molar fractions from 1.8% to 35.6% were produced by fed-batch cultivation of Cupriavidus necator DSM545. Waste glycerol, γ-butyrolactone and propionic acid were used as main carbon source, 4HB and 3HV precursors, respectively. Uniaxial tensile tests were performed on the corresponding biopolymers. The Young's modulus and tensile strength of P(3HB-4HB-3HV) decreased, whereas the elongation at break increased with the 4HB molar%, following the general trend described for poly(3-hydroxybutyrate-4-hydroxybutyrate) (P(3HB-4HB)) but with pronounced lower elasticity. Differential scanning calorimetry results indicate that the temperature of crystallization and enthalpy of melting decreased as the 4HB% increased. No crystallization was observed in terpolymers containing more than 30% of heteromonomers (4HB and 3HV) even though multiple melting events were detected. Terpolymer fractions of different composition were obtained by solvent-fractionation of the original bacterial terpolymers.
authors.affiliation: ICTPOL - Instituto de Ciência e Tecnologia de Polímeros, Av. Rovisco Pais, 1049-001 Lisboa, Portugal; IBB - Institute for Biotechnology and Bioengineering, Instituto Superior Técnico, Universidade Técnica de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa, Portugal.
authors.forename: João M B T
authors.initials: JMBT
authors.lastname: Cavalheiro
authors.affiliation: BioTeam/ICPEES-ECPM, UMR CNRS 7515, Université de Strasbourg, 25 rue Becquerel, 67087 Strasbourg, Cedex 2, France.
authors.forename: Eric
authors.initials: E
authors.lastname: Pollet
authors.affiliation: CQE - Centro de Química Estrutural, Instituto Superior Técnico, Universidade Técnica de Lisboa, 1049-001 Lisboa, Portugal.
authors.forename: Hermínio P
authors.initials: HP
authors.lastname: Diogo
authors.affiliation: ICTPOL - Instituto de Ciência e Tecnologia de Polímeros, Av. Rovisco Pais, 1049-001 Lisboa, Portugal; IBB - Institute for Biotechnology and Bioengineering, Instituto Superior Técnico, Universidade Técnica de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa, Portugal.
authors.forename: M Teresa
authors.initials: MT
authors.lastname: Cesário
authors.affiliation: BioTeam/ICPEES-ECPM, UMR CNRS 7515, Université de Strasbourg, 25 rue Becquerel, 67087 Strasbourg, Cedex 2, France.
authors.forename: Luc
authors.initials: L
authors.lastname: Avérous
authors.affiliation: IBB - Institute for Biotechnology and Bioengineering, Instituto Superior Técnico, Universidade Técnica de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa, Portugal; CIIEM - Centro de Investigação Interdisciplinar Egas Moniz, ISCSEM, Campus Universitário, Quinta da Granja, 2829-511 Monte de Caparica, Portugal.
authors.forename: M Catarina M D
authors.initials: MCMD
authors.lastname: de Almeida
authors.affiliation: IBB - Institute for Biotechnology and Bioengineering, Instituto Superior Técnico, Universidade Técnica de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa, Portugal. Electronic address: manuela.fonseca@ist.utl.pt.
authors.forename: M M R
authors.initials: MMR
authors.lastname: da Fonseca
mesh_terms: D001704:Biopolymers / Q000378:metabolism*; D002152:Calorimetry, Differential Scanning; D002850:Chromatography, Gel; D003460:Crystallization; D020118:Cupriavidus necator / Q000378:metabolism*; D009682:Magnetic Resonance Spectroscopy; D054813:Polyhydroxyalkanoates / Q000378:metabolism*; D013718:Tensile Strength; D013816:Thermodynamics
chemical_list: D001704:Biopolymers; D054813:Polyhydroxyalkanoates
keywords: Mechanical properties; PHA fractionation; Poly(3-hydroxybutyrate-4-hydroxybutyrate-3-hydroxyvalerate); Thermal properties; Waste glycerol