Optimizing a Fed-Batch High-Density Fermentation Process for Medium Chain-Length Poly(3-Hydroxyalkanoates) in...

Area of Science:

• Biotechnology
• Polymer Science
• Microbial Engineering

Background:

• Medium chain-length poly(3-hydroxyalkanoates) (PHA) are promising biobased materials with tunable properties.
• Producing PHA with defined compositions is challenging in native organisms, limiting their applications.
• Existing research lacks high-density cultivation methods for controlled PHA biosynthesis.

Purpose of the Study:

• To develop and optimize a fed-batch fermentation process for producing poly(3-hydroxydecanoate) (PHD) and other PHA polymers.
• To achieve high yields and precise compositional control of PHA polymers using recombinant Escherichia coli.
• To demonstrate the capability of the bioreactor strategy for synthesizing PHA copolymers with specific ratios.

Main Methods:

• Utilized a two-stage fed-batch fermentation process in a stirred tank reactor with recombinant Escherichia coli LSBJ.
• Employed glucose as a co-substrate for growth and various fatty acids for PHA biosynthesis.
• Iteratively optimized media composition and glucose feed rates for enhanced PHA production.

Main Results:

• Achieved high yields of PHD (up to 89.4%) from decanoic acid (20.1 g L⁻¹).
• Successfully polymerized various fatty acids, including hexanoic acid, octanoic acid, 10-undecenoic acid, and 10-bromodecanoic acid, with high yields.
• Demonstrated controlled production of PHA copolymers by co-feeding fatty acids at specific molar ratios.

Conclusions:

• The developed fed-batch fermentation strategy enables high-density cultivation and precise compositional control of PHA polymers.
• This method expands the potential for producing tailored PHA materials with improved properties for diverse applications.
• The bioreactor strategy is effective for synthesizing both homopolymeric and copolymeric PHAs with predictable compositions.