Poly(3-hydroxybutyrate) production in an integrated electromicrobial setup: Investigation under stress-inducing conditions

• Published in: PloS one 2018-04, Vol.13 (4), p.e0196079
• Main Authors: Al Rowaihi, Israa Salem, Paillier, Alexis, Rasul, Shahid, Karan, Ram, Grötzinger, Stefan Wolfgang, Takanabe, Kazuhiro, Eppinger, Jörg
• Format: Article
• Language: English
• Subjects: Analysis; Biodegradability; Biodegradable plastics; Biodegradation; Biology and Life Sciences; Carbon dioxide; Carbon Dioxide - chemistry; Carbon sequestration; Catalysis; Chromatography, Gas; Cupriavidus necator; Cupriavidus necator - metabolism; Cytoplasm; Dehydrogenases; E coli; Earth Sciences; Ecology and Environmental Sciences; Electrochemical Techniques; Electrodes; Electrolysis; Electrolysis (Chemistry); Engineering; Engineering and Technology; Enzymes; Ethanol; Formates - chemistry; Heat resistance; Hydrogen; Hydrogen - chemistry; Hydrogen - metabolism; Hydrogen production; Hydroxybutyrates - analysis; Hydroxybutyrates - metabolism; Metal Nanoparticles - chemistry; Methylobacterium extorquens; Methylobacterium extorquens - metabolism; Microorganisms; Oxidation-Reduction; Oxygen; Physical Sciences; Physiology; Poly-3-hydroxybutyrate; Polyesters - analysis; Polyesters - metabolism; Polyhydroxyalkanoates; Polyhydroxyalkanoic acid; Polyhydroxybutyrate; Polymers; Production processes; Reactive oxygen species; Reactive Oxygen Species - chemistry; Reactive Oxygen Species - metabolism; Salinity; Salinity effects
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0196079

Poly(3-hydroxybutyrate) (PHB), a biodegradable polymer, can be produced by different microorganisms. The PHB belongs to the family of polyhydroxyalkanoate (PHA) that mostly accumulates as a granule in the cytoplasm of microorganisms to store carbon and energy. In this study, we established an integrated one-pot electromicrobial setup in which carbon dioxide is reduced to formate electrochemically, followed by sequential microbial conversion into PHB, using the two model strains, Methylobacterium extorquens AM1 and Cupriavidus necator H16. This setup allows to investigate the influence of different stress conditions, such as coexisting electrolysis, relatively high salinity, nutrient limitation, and starvation, on the production of PHB. The overall PHB production efficiency was analyzed in reasonably short reaction cycles typically as short as 8 h. As a result, the PHB formation was detected with C. necator H16 as a biocatalyst only when the electrolysis was operated in the same solution. The specificity of the source of PHB production is discussed, such as salinity, electricity, concurrent hydrogen production, and the possible involvement of reactive oxygen species (ROS).