Plastic materials are ubiquitous in our daily life. 300 million tons of plastic are produced annually worldwide with a rising tendency of 4%. Plastics as well as glue are made from fossil fuels, which leads to increasing CO2 levels in the atmosphere. Additionally, traditional plastics and glue do not degrade in the environment causing massive pollution of our ecosystems.

So-called bioplastics are a promising alternative to substitute conventional plastic materials. However, in 2017 over 50% of the produced bioplastics (1.2 million) were not biodegradable.

The main focus of the group is the investigation of polyhydroxyalkanoate (PHA) biopolymers, which are produced from renewable resources and are fully biodegradable to CO2 and water in natural environments such as soil and sea. PHAs, polyester with comparable properties to conventional plastic materials, are produced by many microorganism for carbon and energy storage.

Biological glue especially mussel glue enables strong bonding even under water. It is non-toxic, non-mutagenic and biocompatible thus it can be degraded by the human body after medical use.


Riedel, S., Donicz, E., Ferré-Aparicio, P., Santolin, L., Marba Ardebol, A., Neubauer, P., & Junne, S. (2023). Workflow for shake flask and plate cultivations with fats for polyhydroxyalkanoate bioproduction. Applied Microbiology and Biotechnology, 1–13.

Santolin, L., Thiele, I., Neubauer, P., & Riedel, S. L. Tailoring the HHx monomer content of P (HB-co-HHx) by flexible substrate compositions: scale-up from microwell plates to laboratory bioreactor cultivations. Frontiers in Bioengineering and Biotechnology11, 618.

Gutschmann, B., Münzberg, M. and Riedel, S.L. (2023), Bioprozessanalytik: Sondieren, wie der Prozess läuft. Nachr. Chem., 71: 30-32.

Gutschmann, B., Högl, T.H., Huang, B., Maldonado Simões, M., Junne, S., Neubauer, P. et al. (2023) Polyhydroxyalkanoate production from animal by-products: Development of a pneumatic feeding system for solid fat/protein-emulsions. Microbial Biotechnology, 16, 286– 294.

Gutschmann, B., Huang, B., Santolin, L., Thiele, I., Neubauer, P., & Riedel, S. L. (2022). Native feedstock options for the polyhydroxyalkanoate industry in Europe: A review. Microbiological Research, 264, 127177. doi.org

Gutschmann, B., Maldonado Simões, M., Schiewe, T., Schröter, E.S., Münzberg, M., Neubauer, P., Bockisch, A., Riedel, S.L., 2022. Continuous feeding strategy for polyhydroxyalkanoate production from solid waste animal fat at laboratory- and pilot-scale. Microb. Biotechnol.

Santolin, L., Waldburger, S., Neubauer, P., Riedel, S.L., 2021. Substrate-Flexible Two-Stage Fed-Batch Cultivations for the Production of the PHA Copolymer P(HB-co-HHx) With Cupriavidus necator Re2058/pCB113. Front. Bioeng. Biotechnol. 9, 217.

Saad, V., Gutschmann, B., Grimm, T., Widmer, T., Neubauer, P., Riedel, S.L., 2021. Low-quality animal by-product streams for the production of PHA-biopolymers: fats, fat/protein-emulsions and materials with high ash content as low-cost feedstocks. Biotechnol. Lett. 43, 579–587.

Gutschmann, B., Bock, M.C.E., Jahns, S., Neubauer, P., Brigham, C.J., Riedel, S.L., 2021. Untargeted metabolomics analysis of Ralstonia eutropha during plant oil cultivations reveals the presence of a fucose salvage pathway. Sci. Rep. 11, 1–12.

Riedel, S.L., Brigham, C.J., 2020. Inexpensive and Waste Raw Materials for PHA Production, in: Koller, M. (Ed.), The Handbook of Polyhydroxyalkanoates. CRC Press, Boca Raton, pp. 203–221.

Bartels, M., Gutschmann, B., Widmer, T., Grimm, T., Neubauer, P., Riedel, S.L., 2020. Recovery of the PHA Copolymer P(HB-co-HHx) With Non-halogenated Solvents: Influences on Molecular Weight and HHx-Content. Front. Bioeng. Biotechnol. 8, 1–12.

Riedel, S.L., Brigham, C., 2019. Polymers and adsorbents from agricultural waste, in: Simpson, B.K., Aryee, A.N.A., Toldrá, F. (Eds.), Byproducts from Agriculture and Fisheries: Adding Value for Food, Feed, Pharma and Fuels. Wiley, Chichester, pp. 523–544.

Gutschmann, B., Schiewe, T., Weiske, M.T.H., Neubauer, P., Hass, R., Riedel, S.L., 2019. In-Line Monitoring of Polyhydroxyalkanoate (PHA) Production during High-Cell-Density Plant Oil Cultivations Using Photon Density Wave Spectroscopy. Bioengineering 6, 85.

Ong, S.Y., Kho, H.P., Riedel, S.L., Kim, S.W., Gan, C.Y., Taylor, T.D., Sudesh, K., 2018. An integrative study on biologically recovered polyhydroxyalkanoates (PHAs) and simultaneous assessment of gut microbiome in yellow mealworm. J. Biotechnol. 265, 31–39.

Brigham, C.J., Riedel, S.L., 2018. The Potential of Polyhydroxyalkanoate Production from Food Wastes. Appl. Food Biotechnol. 6, 7–18.

Riedel, S.L., Jahns, S., Koenig, S., Bock, M.C.E., Brigham, C.J., Bader, J., Stahl, U., 2015. Polyhydroxyalkanoates production with Ralstonia eutropha from low quality waste animal fats. J. Biotechnol. 214, 119–127.

Riedel, S.L., Lu, J., Stahl, U., Brigham, C.J., 2014. Lipid and fatty acid metabolism in Ralstonia eutropha: Relevance for the biotechnological production of value-added products. Appl. Microbiol. Biotechnol. 98, 1469–1483.

Riedel, S.L., Brigham, C.J., Budde, C.F., Bader, J., Rha, C., Stahl, U., Sinskey, A.J., 2013. Recovery of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) from Ralstonia eutropha cultures with non-halogenated solvents. Biotechnol. Bioeng. 110, 461–470.

Riedel, S.L., Bader, J., Brigham, C.J., Budde, C.F., Yusof, Z.A.M., Rha, C., Sinskey, A.J., 2012. Production of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) by Ralstonia eutropha in high cell density palm oil fermentations. Biotechnol. Bioeng. 109, 74–83.

Budde, C.F., Riedel, S.L., Hübner, F., Risch, S., Popović, M.K., Rha, C., Sinskey, A.J., 2011a. Growth and polyhydroxybutyrate production by Ralstonia eutropha in emulsified plant oil medium. Appl. Microbiol. Biotechnol. 89, 1611–1619.

Budde, C.F., Riedel, S.L., Willis, L.B., Rha, C., Sinskey, A.J., 2011b. Production of Poly(3-Hydroxybutyrate- co -3-Hydroxyhexanoate) from Plant Oil by Engineered Ralstonia eutropha Strains. Appl. Environ. Microbiol. 77, 2847–2854.

Running Projects



PHABio-up aims to succeed the acceleration of the industrial production of biodegradable Polyhydroxyalkanoate (PHA) biopolymers from biogenic feedstocks.



PHAcoat strives to create a versatile production process for Polyhydroxyalkanoate (PHA) biodegradable bioplastics, specifically designed to meet the demands of fibers for functional textiles and coatings for sustainable packaging alternatives.

Contact person

M. Sc. Saskia Waldburger 


Project supervisor

Prof. Dr.-Ing. Sebastian L. Riedel (



Former Projects


PHAbio App

PHAbio APP aims the development of a closed circle for the production, processing, recycling and biodegradation of novel PHA biopolymers from biowaste, in particular fat waste.


Mussel glue is outstanding because it enables even under water extremely strong bonding. Till now, it was a problem to produce the glue in higher amounts and when produced it was sticking everywhere, that it was difficult to handle.



PHAtex aims to develop a complete green process chain to produce novel, flexible and biodegradable polyhydroxyalkanoate (PHA) textile filaments on a competitive basis from renewable feedstocks.