Archaeal production of polyhydroxyalkanoate (PHA) co- and terpolyesters from biodiesel industry-derived by-products.
The archaeon Haloferax mediterranei was selected for production of PHA co- and terpolyesters using inexpensive crude glycerol phase (CGP) from biodiesel production as carbon source. CGP was assessed by comparison with the application of pure glycerol. Applying pure glycerol, a copolyester with a molar fraction of 3-hydroxybutyrate (3HB) of 0.90 mol/mol and 3-hydroxyvalerate (3HV) of 0.10 mol/mol, was produced at a volumetric productivity of 0.12 g/Lh and an intracellular PHA content of 75.4 wt.-% in the sum of biomass protein plus PHA. Application of CGP resulted in the same polyester composition and volumetric productivity, indicating the feasibility of applying CGP as feedstock. Analysis of molar mass distribution revealed a weight average molar mass M w of 150 kDa and polydispersity P i of 2.1 for pure glycerol and 253 kDa and 2.7 for CGP, respectively; melting temperatures ranged between 130 and 140°C in both setups. Supplying γ -butyrolactone as 4-hydroxybutyrate (4HB) precursor resulted in a poly[(R)-3-hydroxybutyrate-co-(R)-3-hydroxyvalerate-co-4-hydroxybutyrate] (PHBHV4HB) terpolyester containing 3HV (0.12 mol/mol) and 4HB (0.05 mol/mol) in the poly[(R)-3-hydroxybutyrate] (PHB) matrix; in addition, this process runs without sterilization of the bioreactor. The terpolyester displayed reduced melting (melting endotherms at 122 and 137°C) and glass transition temperature (2.5°C), increased molar mass (391 kDa), and a polydispersity similar to the copolyesters.
Institute of Biotechnology and Biochemical Engineering, Graz University of Technology, Petersgasse 12, 8010 Graz, Austria.
Carmen
C
Hermann-Krauss
Institute of Biotechnology and Biochemical Engineering, Graz University of Technology, Petersgasse 12, 8010 Graz, Austria ; ARENA Arbeitsgemeinschaft für Ressourcenschonende und Nachhaltige Technologien, Inffeldgasse 23, 8010 Graz, Austria ; Institute of Chemistry, Karl-Franzens University of Graz, Heinrichstrasse 28, 8010 Graz, Austria.
Martin
M
Koller
Polymer Competence Center Leoben GmbH, c/o Petersgasse 12, 8010 Graz, Austria ; Institute for Chemistry and Technology of Materials, Graz University of Technology, Stremayrgasse 9, 8010 Graz, Austria.
Alexander
A
Muhr
Institute for Chemistry and Technology of Materials, Graz University of Technology, Stremayrgasse 9, 8010 Graz, Austria.
Hubert
H
Fasl
Polymer Competence Center Leoben GmbH, c/o Petersgasse 12, 8010 Graz, Austria ; Institute for Chemistry and Technology of Materials, Graz University of Technology, Stremayrgasse 9, 8010 Graz, Austria.
Franz
F
Stelzer
Institute of Biotechnology and Biochemical Engineering, Graz University of Technology, Petersgasse 12, 8010 Graz, Austria ; ARENA Arbeitsgemeinschaft für Ressourcenschonende und Nachhaltige Technologien, Inffeldgasse 23, 8010 Graz, Austria.
Gerhart
G
Braunegg
D020155:3-Hydroxybutyric Acid / Q000096:biosynthesis; D015107:4-Butyrolactone / Q000737:chemistry / Q000378:metabolism; D063566:Biodegradable Plastics / Q000737:chemistry / Q000378:metabolism; D056804:Biofuels; D005990:Glycerol / Q000737:chemistry / Q000378:metabolism*; D019623:Haloferax mediterranei / Q000378:metabolism*; D006885:Hydroxybutyrates / Q000737:chemistry / Q000378:metabolism; D010421:Pentanoic Acids / Q000737:chemistry / Q000378:metabolism; D011091:Polyesters / Q000737:chemistry / Q000378:metabolism*; D054813:Polyhydroxyalkanoates / Q000096:biosynthesis*; D000094122:Polyhydroxybutyrates
D020155:3-Hydroxybutyric Acid; D015107:4-Butyrolactone; D063566:Biodegradable Plastics; D056804:Biofuels; D005990:Glycerol; D006885:Hydroxybutyrates; D010421:Pentanoic Acids; D011091:Polyesters; D054813:Polyhydroxyalkanoates; C510062:poly(3-hydroxybutyrate-co-3-hydroxyvalerate-co-4-hydroxybutyrate); D000094122:Polyhydroxybutyrates; C013056:beta-hydroxyvaleric acid; C111420:4-hydroxybutyric acid