Liquefied Wood as Inexpensive Precursor-Feedstock for Bio-Mediated Incorporation of (R)-3-Hydroxyvalerate into Polyhydroxyalkanoates
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European Commisision's projectANIMPOL - Biotechnological conversion of carbon containing wastes for eco-efficient production of high added value products (EC-FP7-245084)
Liquefied wood (LW) prepared in a microwave process was applied as a novel; inexpensive precursor feedstock for incorporation of (R)-3-hydroxyvalerate (3HV) into polyhydroxyalkanoate (PHA) biopolyesters in order to improve the biopolyester's material quality; Cupriavidus necator was applied as microbial production strain. For proof of concept, pre-experiments were carried out on a shake flask scale using different mixtures of glucose and LW as carbon source. The results indicate that LW definitely acts as a 3HV precursor, but, at the same time, displays toxic effects on C. necator at concentrations exceeding 10 g/L. Based on these findings, PHA biosynthesis under controlled conditions was performed using a fed-batch feeding regime on a bioreactor scale. As major outcome, a poly(3HB-co-0.8%-3HV) copolyester was obtained displaying a desired high molar mass of M-w = 5.39 x 10(5) g/mol at low molar-mass dispersity (D-M of 1.53), a degree of crystallinity (X-c) of 62.1%, and melting temperature T-m (176.3 degrees C) slightly lower than values reported for poly([R]-3-hydroxybutyrate) (PHB) homopolyester produced by C. necator; thus, the produced biopolyester is expected to be more suitable for polymer processing purposes.
CitationKoller, M., Miranda-de Sousa Dias, M., Rodriguez, A., Kunaver, M., Zagar, E., Krzan, A., Braunegg, G. Liquefied Wood as Inexpensive Precursor-Feedstock for Bio-Mediated Incorporation of (R)-3-Hydroxyvalerate into Polyhydroxyalkanoates. "Materials", 01 Setembre 2015, vol. 8, núm. 9, p. 6543-6557.