Polyhydroxyalkanoates

Polyhydroxyalkanoates are biodegradable polyesters that have the potential to replace conventional petrochemical plastics such as polyethylene in many applications.

As is to be expected with hydroxy fatty acid esters, a variety of organic acids are suitable for the production of PHAs. As these occur as degradation products of organic waste and wastewater, among other things, PHA processes are ideal for obtaining raw materials from residual materials [1, 2].

Classic producers are the bacteria Cupriavidus necator or Pseudomonas sp.. However, unusual representatives such as archaea, phototrophic bacteria and micro-algae also have the ability to accumulate this fascinating raw material as a carbon store [3].

A large number of different production organisms and polymer compositions allow a wide range of starting materials and property profiles of the product to be utilized.
Since PHAs are an entire class of substances, they are divided into three large groups, the short-chain-length PHAs (scL-PHAs), with 4-5 carbon atoms per monomer unit, the middle-chain-length PHAs (mcl-PHA), with 6-14 carbon atoms and the long-chain-length PHAs (lcl-PHA) for longer monomer units. The flexibility, melting temperature and other properties depend on the length of the carbon chain of the PHA monomer [4, 5].

In addition to the base polymer polyhydroxybutyrate (PHB), the focus at the IGVP is primarily on the development of co-polymers with an increased hydroxyvalerate content.
Due to its heterogeneous composition, the polyhydroxybutyrate co-hydroxyvalerate (PHBV) is less crystalline than the PHB homopolymer, which gives it increased flexibility. The property profile of the bioplastic can be adjusted via the proportion of co-polymer units [6].

The institutes are also working on fermentation with a high cell density and optimizing the substrate supply in order to increase PHA production.

1. Tamang, P., et al., Comparative study of polyhydroxyalkanoates production from acidified and anaerobically treated brewery wastewater using enriched mixed microbial culture. J Environ Sci (China), 2019. 78: p. 137-146.
2. Yun, J.H., S.S. Sawant, and B.S. Kim, Production of polyhydroxyalkanoates by Ralstonia eutropha from volatile fatty acids. KOREAN JOURNAL OF CHEMICAL ENGINEERING, 2013. 30(12): p. 2223-2227.
3. Alves, A.A., et al., Polyhydroxyalkanoates: a review of microbial production and technology application. International journal of environmental science and technology, 2022.
4. Reddy, V.U.N., et al., Review of the Developments of Bacterial Medium-Chain-Length Polyhydroxyalkanoates (mcl-PHAs). Bioengineering (Basel), 2022. 9(5).
5. Andreessen, B., N. Taylor, and A. Steinbüchel, Poly(3-hydroxypropionate): a promising alternative to fossil fuel-based materials. Appl Environ Microbiol, 2014. 80(21): p. 6574-82.
6. Zhila, N.O., et al., Biosynthesis and Properties of a P(3HB-co-3HV-co-4HV) Produced by Cupriavidus necator B-10646. POLYMERS, 2022. 14(19).

• Mustermengenproduktion von PHAs aus nachwachsendem Rohstoff
• Evaluation der Verwertungsmöglichkeit von organischen Restströmen
• Entwicklung von Co-Polymeren mit verschiedene monomer Anteil
• Scale-up und Prozessentwicklung