VOLATIL - Integrated Two-Step Fermentation Processes for the Utilization of Waste Streams in Biorefineries

Despite significant progress in the development of production strains and fermentation processes, commercial biorefineries using second-generation (2G) feedstocks are still hard to find. When analyzing the ongoing difficulties in establishing second-generation biorefineries, two main obstacles can be identified: First, organic waste streams often contain inhibitors and therefore need to be diluted to serve as substrates for microbial growth. Therefore, the end product titers of such fermentations are often low, which makes downstream processing expensive. Secondly, the chemical composition of the waste streams is often poorly defined. They consist of a complex matrix of mineral salts and organic substances, only some of which can be utilized by microorganisms. Compounds that are not utilized by the production strains often remain in the fermentation medium and are ultimately found in the end product. The consequences of these impurities range from deviations from the desired color of the product to its complete uselessness in subsequent processing stages. From an economic point of view, this means disproportionately high costs for product purification or even a complete failure of the technology.

In the present project we will solve these problems by developing a two-stage fermentation process in which in the first stage a waste stream is fermented into a carrier molecule. In the second stage, this carrier molecule is converted to 3-hydroxypropionic acid (3HP), the precursor of acrylic acid and biodegradable plastics.