Fed-batch production of MCL-PHA with elevated 3-hydroxynonanoate content

Area of Science:

• Microbial Biotechnology
• Polymer Science
• Metabolic Engineering

Background:

• Pseudomonas putida KT2440 naturally produces medium-chain-length poly(3-hydroxyalkanoate) (MCL-PHA).
• Achieving high 3-hydroxynonanoate (HN) content in MCL-PHA is desirable for specific material properties.
• Controlling the monomeric composition of PHA is crucial for tailoring its characteristics.

Purpose of the Study:

• To enhance the production of MCL-PHA with higher HN content.
• To achieve adjustable monomeric composition in PHA by inhibiting fatty acid beta-oxidation.
• To optimize fed-batch fermentation conditions for high-yield PHA production.

Main Methods:

• Utilized acrylic acid as a beta-oxidation inhibitor in fed-batch fermentations.
• Co-substrate feeding strategy involving nonanoic acid, glucose, and acrylic acid.
• Varied feeding conditions to control specific growth rates and inhibitor concentrations.

Main Results:

• Achieved PHA production with up to 89 mol% HN content.
• Demonstrated adjustable monomeric composition by manipulating feeding strategies.
• Obtained 71.4 g L-1 biomass with 75.5% PHA content at a cumulative productivity of 1.8 g L-1 h-1.

Conclusions:

• Acrylic acid effectively inhibits beta-oxidation, enabling high HN content in MCL-PHA.
• Fed-batch fermentation with controlled conditions allows for tunable PHA monomeric composition.
• This strategy offers a viable route for producing tailored MCL-PHA from nonanoic acid.