Biosynthesis of functional polyhydroxyalkanoates by engineered Halomonas bluephagenesis

Area of Science:

• Industrial Biotechnology
• Polymer Science
• Microbial Engineering

Background:

• Polyhydroxyalkanoates (PHA) are biodegradable polymers with medical applications, but require functional groups for modification.
• Halomonas bluephagenesis is a halophilic bacterium utilized as a chassis for industrial biotechnology.
• Engineering PHA synthesis in non-model bacteria is crucial for producing functional biopolymers.

Purpose of the Study:

• To engineer Halomonas bluephagenesis for the synthesis of functional polyhydroxyalkanoates (PHA) copolymers.
• To optimize the production of PHA with specific functional side chains, such as 3-hydroxyhexenoate (3HHxE).
• To establish a platform strain for the production of tailored PHA for advanced applications.

Main Methods:

• Genetic engineering of Halomonas bluephagenesis to express heterologous PHA synthase (PhaC) and enoyl-CoA hydratase (PhaJ).
• Deletion of native phaC gene and introduction of endogenous acyl-CoA synthetase (fadD).
• Fermentation optimization using glucose and 5-hexenoic acid as co-substrates.

Main Results:

• Achieved a high 3HHxE molar ratio of 35% in PHA copolymers.
• Produced terpolymers with up to 44% total side chain monomers (3-hydroxyhexanoate and 3HHxE).
• Generated functional PHA with 12.5 mol% 3-hydroxy-5-hexenoate, exhibiting over 1000% elongation at break.

Conclusions:

• Engineered H. bluephagenesis TDR4 is a viable platform for producing functional PHA with tunable properties.
• The high 3HHxE content in PHA enhances material properties like elongation at break.
• This work advances the production of customized biopolymers for diverse applications.