title: Feasibility study of an alkaline-based chemical treatment for the purification of polyhydroxybutyrate produced by a mixed enriched culture.
abstract: This study focused on investigating the feasibility of purifying polyhydroxybutyrate (PHB) from mixed culture biomass by alkaline-based chemical treatment. The PHB-containing biomass was enriched on acetate under non-sterile conditions. Alkaline treatment (0.2 M NaOH) together with surfactant SDS (0.2 w/v% SDS) could reach 99% purity, with more than 90% recovery. The lost PHB could be mostly attributed to PHB hydrolysis during the alkaline treatment. PHB hydrolysis could be moderated by increasing the crystallinity of the PHB granules, for example, by biomass pretreatment (e.g. freezing or lyophilization) or by effective cell lysis (e.g. adjusting alkali concentration). The suitability of the purified PHB by alkaline treatment for polymer applications was evaluated by molecular weight and thermal stability. A solvent based purification method was also performed for comparison purposes. As result, PHB produced by mixed enriched cultures was found suitable for thermoplastic applications when purified by the solvent method. While the alkaline method resulted in purity, recovery yield and molecular weight comparable to values reported in literature for PHB produced by pure cultures, it was found unsuitable for thermoplastic applications. Given the potential low cost and favorable environmental impact of this method, it is expected that PHB purified by alkaline method may be suitable for other non-thermal polymer applications, and as a platform chemical.
authors: Department of Biotechnology, Delft University of Technology, Julianalaan 67, 2628 BC Delft, The Netherlands.
authors: Yang
authors: Y
authors: Jiang
authors: Polymer Technology Group Eindhoven BV, De Lismortel 31, 5612 AR Eindhoven, The Netherlands.
authors: Gizela
authors: G
authors: Mikova
authors: Department of Biotechnology, Delft University of Technology, Julianalaan 67, 2628 BC Delft, The Netherlands.
authors: Robbert
authors: R
authors: Kleerebezem
authors: Department of Biotechnology, Delft University of Technology, Julianalaan 67, 2628 BC Delft, The Netherlands.
authors: Luuk Am
authors: LA
authors: van der Wielen
authors: Department of Biotechnology, Delft University of Technology, Julianalaan 67, 2628 BC Delft, The Netherlands.
authors: Maria C
authors: MC
authors: Cuellar
keywords: Alkaline treatment; Crystallinity; Mixed cultures; Polyhydroxybutyrate; Thermal stability
references: Water Res. 2005 May;39(10):2076-84
references: 15913705
references: Chem Soc Rev. 2009 Aug;38(8):2434-46
references: 19623359
references: Biotechnol Lett. 2003 Jan;25(1):55-9
references: 12882307
references: Appl Environ Microbiol. 2009 Feb;75(3):643-51
references: 19047387
references: Biomacromolecules. 2009 Apr 13;10(4):670-6
references: 19193058
references: Water Res. 2010 Jun;44(11):3419-33
references: 20427069
references: J Biotechnol. 2007 Nov 1;132(3):251-8
references: 17532079
references: Appl Environ Microbiol. 1993 Dec;59(12):4236-44
references: 16349121
references: Biotechnol Prog. 2006 Mar-Apr;22(2):547-53
references: 16599575
references: Int J Syst Evol Microbiol. 2011 Sep;61(Pt 9):2314-9
references: 20971833
references: Bacteriol Rev. 1957 Sep;21(3):195-213
references: 13471458
references: Biotechnol Lett. 2011 May;33(5):937-42
references: 21207109
references: Int J Biol Macromol. 1999 Jun-Jul;25(1-3):207-15
references: 10416669
references: Macromol Biosci. 2008 Apr 9;8(4):355-66
references: 18157852
references: Biotechnol Bioeng. 2013 Feb;110(2):461-70
references: 22903730
references: Water Res. 2012 Nov 1;46(17):5517-30
references: 22921584
references: Appl Biochem Biotechnol. 2012 Jun;167(3):524-35
references: 22569781
references: Int J Biol Macromol. 1992 Feb;14(1):50-6
references: 1596472
references: Macromol Biosci. 2006 Nov 9;6(11):885-906
references: 17099863
references: J Microbiol Methods. 2006 Nov;67(2):212-9
references: 16753235
references: Biotechnol Bioeng. 1999 Mar 5;62(5):546-53
references: 10099563
references: Bioresour Technol. 2008 Feb;99(3):509-16
references: 17360180