Characterisation of polyhydroxyalkanoate copolymers with controllable four-monomer composition

Yu Dai, Lambert, L., Yuan, Zhiguo and Keller, Jurg (2008) Characterisation of polyhydroxyalkanoate copolymers with controllable four-monomer composition. Journal of Biotechnology, 134 1-2: 137-145. doi:10.1016/j.jbiotec.2008.01.013


Author Yu Dai
Lambert, L.
Yuan, Zhiguo
Keller, Jurg
Title Characterisation of polyhydroxyalkanoate copolymers with controllable four-monomer composition
Journal name Journal of Biotechnology   Check publisher's open access policy
ISSN 1873-4863
Publication date 2008-03-20
Year available 2008
Sub-type Article (original research)
DOI 10.1016/j.jbiotec.2008.01.013
Open Access Status DOI
Volume 134
Issue 1-2
Start page 137
End page 145
Total pages 9
Place of publication Amsterdam, The Netherlands
Publisher Elseiver Science
Language eng
Subject C1
969999 Environment not elsewhere classified
090409 Wastewater Treatment Processes
10 Technology
Abstract Polyhydroxyalkanoate (PHA) copolymers comprising the four monomers 3-hydroxybutyrate (3HB), 3-hydroxyvalerate (3HV), 3-hydroxy-2-methylvalerate (3HMV) and 3-hydroxy-2-methylbutyrate (3HMB) were generated using the recently discovered Defluviicoccus vanus-related glycogen accumulating organisms (DvGAOs) under anaerobic conditions without applying any nutrient limitations. The composition could be manipulated in a defined range by modifying the ratio of propionate and acetate provided in the feed stream. The PHAs produced were characterised as random copolymers (from propionate alone) or a mixture of random copolymers (from mixture of propionate and acetate) through microstructure analysis using C-13 NMR spectroscopy. The sequence distribution of all eight comonomer pairs in the carbonyl region of 3HB and 3HV was identified and assigned with confidence utilising two-dimensional heteronuclear multiple bond coherence (HMBC) spectroscopy. Weight average molecular weights were in the range 390-560 kg/mol. Differential scanning calorimetry (DSC) traces showed that the melting temperature (T-m) varied between 70 and 161 degrees C and glass transition temperature (T-g) ranged from -8 to 0 degrees C. The incorporation of considerable amounts of 3HMV and 3HMB monomer units introduced additional "defects" into the PHBV copolymer structure and hence greatly lowered the crystallinity. The data indicate the potential of these four-monomer PHAs to be employed for practical applications, considering their favourable properties and the cost-effective production process using a mixed culture and simple carbon sources. (C) 2008 Elsevier B.V. All rights reserved.
Formatted abstract
Polyhydroxyalkanoate (PHA) copolymers comprising the four monomers 3-hydroxybutyrate (3HB), 3-hydroxyvalerate (3HV), 3-hydroxy-2-methylvalerate (3HMV) and 3-hydroxy-2-methylbutyrate (3HMB) were generated using the recently discovered Defluviicoccus vanus-related glycogen accumulating organisms (DvGAOs) under anaerobic conditions without applying any nutrient limitations. The composition could be manipulated in a defined range by modifying the ratio of propionate and acetate provided in the feed stream. The PHAs produced were characterised as random copolymers (from propionate alone) or a mixture of random copolymers (from mixture of propionate and acetate) through microstructure analysis using 13C NMR spectroscopy. The sequence distribution of all eight comonomer pairs in the carbonyl region of 3HB and 3HV was identified and assigned with confidence utilising two-dimensional heteronuclear multiple bond coherence (HMBC) spectroscopy. Weight average molecular weights were in the range 390–560 kg/mol. Differential scanning calorimetry (DSC) traces showed that the melting temperature (Tm) varied between 70 and 161 °C and glass transition temperature (Tg) ranged from −8 to 0 °C. The incorporation of considerable amounts of 3HMV and 3HMB monomer units introduced additional “defects” into the PHBV copolymer structure and hence greatly lowered the crystallinity. The data indicate the potential of these four-monomer PHAs to be employed for practical applications, considering their favourable properties and the cost-effective production process using a mixed culture and simple carbon sources.
Copyright © 2008 Elsevier B.V. All rights reserved.

Keyword PHA
Copolymer
GAOs
NMR
Melting temperature
Molecular weight
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ

 
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Created: Thu, 16 Apr 2009, 00:42:12 EST by Suzanne Read on behalf of Advanced Water Management Centre