Production of polyhydroxyalkanoates by purple phototrophic bacteria using
Production of polyhydroxyalkanoates by purple phototrophic bacteria using wastewater treatment products Guillaume Bayon-Vicente (guillaume. bayon-vicente@umons. ac. be)
Polyhydroxyalkanoates, future worldwide plastics ? Pros Bio-based Packaging Biodegradable Agriculture Broad range of applications Dentistry Drug delivery
How are they produced now ?
Rhodospirillum rubrum, future PHA producer model ? Photosynthesis repressed by presence of oxygen High metabolic versatility (photoheterotrophy, photoautotrophy, chemoheterotrophy) Assimilation of a wide range of carbon sources Volatil fatty acids (VFAs) Acetic Propionic acid (C 2) (C 3) Butyric Valeric acid (C 4) (C 5)
Rhodospirillum rubrum, future PHA producer model ? Poly(hydroxybutyrate-co-hydroxyvalerate)
Our bioprocess advantages
Working hypotheses Reduced carbon sources Photoreduction of NAD+ Redox state NAD(P)H H+ Biomass NAD(P)+ H+ Carbon source NADH dehydrogenase ATP synthase ADP + Pi ATP Electron sink Pha. A Pha. C Pha. B NAD+ NADH
1. Use of reduced carbon source
The assimilation of valeric acid Compounds Formule Redox state Malate C 4 H 6 O 5 +2 Pyruvate C 4 H 6 O 4 +1 Acetic acid C 2 H 4 O 2 0 CH 1. 7 O 0. 4 N 0. 2 S 0. 003 P 0. 01 -0, 45 Propionic acid C 3 H 6 O 2 -1 Butyric acid C 4 H 8 O 2 -2 Valeric acid C 5 H 10 O 2 -3 Biomass Production of the high added value compound poly(hydroxybutyrate-co-hydroxyvalerate) (P(HB-co-HV))
The assimilation of valeric acid Excess of HCO 3 - is mandatory for Rs. rubrum growth is presence of valerate
The assimilation of valeric acid Excess of HCO 3 - Progressive adding of HCO 33 m. M HCO 3 - Alternation between suitable and non suitable redox environmental conditions increases PHA production
2. Impact of light regime
Impact of light regime Acetate Competence strain – tolerant to high light intensity 50 µmol photons/m² s 50 150 µmol photons/m²s Light regime switch has no impact on PHA production
Impact of light regime Wild type strain 50 µmol photons/m² s 50 150 µmol photons/m²s Light regime switch has an impact on PHA production
3. PHA produced in mix of VFAs
Mix VFAs – Composition of the medium 10% Acetic acid 44% 13% Propionic acid Butyric acid Isovaleric acid Valeric acid 23%
Mix VFAs – Composition of the medium
4. Conclusion and future prospects
Conclusion Intracellular redox state Redox state NAD(P)H NAD(P)+ Biomass Environment Carbon source PHA production
Further Prospects Volatile fatty acids Fermentation phenomenon PHA production Pigment production
Acknowledgement Co-Supervisor Me Baptiste. leroy@umons. ac. be Guillaume. bayon-vicente@umons. ac. be Supervisor Ruddy. wattiez@umons. ac. be
Associating high production with high added value Possibility of fine tuning of obtained PHA
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