Efficacy of medium chain-length polyhydroxyalkanoate biosynthesis from different biochemical pathways under oxygen-limited conditions using Pseudomonas putida LS46. (July 2019)

• Record Type: Journal Article
• Authors: Blunt, Warren; Lagassé, Alain; Jin, Zimo; Dartiailh, Christopher; Sparling, Richard; Gapes, Daniel J.; Levin, David B.; Cicek, Nazim
• Is Part Of: Process biochemistry. Volume 82(2019)
• Page Start: 19
• Page End: 31
• Publication Date: 2019-07
• Subjects: Polyhydroxyalkanoates -- Microaerophilic -- de novo biosynthesis -- β-oxidation; Biochemical engineering -- Periodicals; Biotechnology -- Periodicals; Biochemistry -- periodicals; Biotechnology -- periodicals; Chemical Engineering -- periodicals; Génie biochimique -- Périodiques; Biotechnologie -- Périodiques; Biochemical engineering; Biotechnology; Periodicals; 660.63
• DOI: 10.1016/j.procbio.2019.04.013
• Languages: English
• ISSNs: 1359-5113

Abstract

Graphical abstract: Highlights: Mcl-PHA biosynthesis from different central metabolic routes was tested at low DO. De novo mcl-PHA synthesis was not induced by oxygen limitation in P. putida LS46. The content of monomers from β-oxidation intermediates was enriched at low DO. The oxygen transfer rate could be used to control the content of certain monomers. Abstract: Biosynthesis of medium chain length polyhydroxyalkanoates (mcl-PHAs) requires oxygen, but little is known of how mcl-PHA production is impacted in low dissolved oxygen (DO) environments, particularly when synthesized from monomers obtained via a de novo pathway. Growth and mcl-PHA synthesis characteristics under microaerophilic bioreactor conditions were observed in Pseudomonas putida LS46 when grown on carbon substrates requiring a de novo pathway, to varying extent, for mcl-PHA synthesis. Negligible PHA accumulated from glucose, acetic acid, or valeric acid under oxygen limitation (DO ≤ 0.15 mg L −1 ), while final mcl-PHA content reached 19.5% of cell dry mass (CDM) from hexanoic acid. The C6 content of the polymer obtained under low DO was 10% higher than in a DO excess (NH4 -limited) control experiment, with less of the C10 monomers indicative of de novo synthesis. In all cases, the carbon-to-PHA yield was poor (< 0.1 C-mol C-mol −1 ). We conclude that, as opposed to utilizing β-oxidation intermediates, de novo biosynthesis of mcl-PHA using P. putida LS46 is not favorable in microaerophilic environments. In addition to scale-up implications, this work also suggests that lowering the bioreactor oxygen transfer rate can decrease the contribution of monomers incorporated using de novo synthesis for carbon feedstocks with mixed composition.