Polyhydroxyalkanoates (PHAs) are biodegradable biopolyesters that are accumulated by some bacteria as intracellular carbon and energy storage compounds. Depending on the substrate composition (e.g., sugars, fatty acids) and the production strain, different types of PHAs with individual fields of application can be produced: fluidoplasts (glue), elastomers (coatings), or thermoplasts (fibers, solid products).
The goal of this project is to identify waste streams from the food industry that can be converted into inexpensive, non-food competitive substrates for the production of PHAs. The pomace of white grapes (Solaris, Gewürztraminer) and waste frying oil were shown to be especially promising due to their low cost, high availability, low bacterial toxicity, and high content of fermentable/PHA convertible carbon. Successful fermentations were carried out using these biowastes either individually or sequentially, and the scalability of the overall process was demonstrated up to a cultivation volume of 100 L.