Sustainable PHA polymer production through microbial fermentation

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Sustainable PHA polymer production through microbial fermentation.


Petroleum-based plastics are valuable materials that are used in the majority of the industries worldwide. Because they are chemically stable and versatile, they are durable and can be used in an extensive number of industries. These plastics are cost effective, easy to produce and dispose of after use. However, they are non-biodegradable, accumulating in the environment for hundreds of years before full degradation.
Polyhydroxyalkanoates (PHA) are a family of polymers that can be synthesized by microorganisms and can be completely biodegraded into CO2 and H2O. Over 150 different monomers have been discovered, and depending on the monomeric composition of the PHA, they can have an extensive range of properties. PHA are thermoplastics with similar properties as the petroleum-based plastics.
At the moment, PHA are produced at full-scale production using single microbial cultures and sugar-based feedstocks. A wide variety of monomers can also be produced using this current technology. However, this current process is quite expensive and an alternative using mixed microbial cultures (MMC) has arisen as a more cost-effective technology.


Using the typical 3-stage process for PHA production, sterilization is not necessary, thereby decreasing the overall costs of production of PHA in comparison to pure culture systems. Using this technology, a mixture of two monomers is often produced as a result: 3-hydroxybutyrate and 3-hydroxyvalerate, which are both short-chain length PHA (scl-PHA).
Herein described is a medium-chain length PHA, a polymer containing 3-hydroxyhexanoate and its method of production and uses thereof. Due to the existence of medium-chain length monomer, this proprietary polymer possesses different properties than polymers containing only short-chain length monomers. This polymer has a molecular weight of 7.90 x 105 Da and a PDI of 1.62. Additionally, it has a tensile strength at break of 5.15 MPa, elongation to break of 269% as well as a Young modulus of 0.78 MPa, which results in improved flexibility and elastomeric properties, a high degree of elongation to break and improved biocompatibility with respect to polyhydroxybutyrate, making them suitable for a different range of applications as compared to scl-PHA.


TRL 5 – technology validated in relevant environment.


Potentially cheaper in comparison to pure culture systems;
Sustainable alternative to oil-based plastics;
Improved properties in comparison to scl-PHA, a wide range of applications.


Packaging films (e.g. bags, containers and paper coatings);
Pharmaceuticals and cosmetics;
Agriculture and forestry;
Construction materials, disposable utensils, fishing equipment, machinery housings, photography techniques.


Seeking for partners for process development and/or Licence agreement for commercialization for multiple applications


Medium-chain length polyhydroxyalkanoates; mcl-PHA; 3-hydroxyhexanoate; mixed microbial cultures; MMC; PHA; caproate; caproic acid; hexanoate; hexanoic acid.


NOVA Inventors

Maria Ascenção Reis


Academic Information | NOVA School of Science and Technology | FCT NOVA