Technische Universität Berlin

TUB has a large experience in bioprocess scale up and scale down, microbial process development and PAT. Bioeconomy-based processes, that are currently developed or optimized with the use of parallel reactors, liquid handling systems and innovative process analytical tools are PHA production with Ralstonia eutropha (PHAbio_APP), polyunsaturated fatty acids with the heterotrophic algae Cryptecodinium cohnii for fish feed (FENA) and lysine production with Corynebacterium glutamicum (SCILS).

Together with the Berlin-based small enterprise EloSystems, TUB has developed a monitoring tool to evaluate the polarizability of bacterial, rod-shaped cells. Unfavourable growth conditions can be detected very early. Results are published for the ABE fermentation with C. acetobutylicum, E. coli batch cultivation and recently for anaerobic digestion. TUB will adopt this methodology to enable a flexible process for waste conversion, which is robust against fluctuating substrate composition and quality in a continuous process mode as repeated batch. With this strategy, food waste shall be applicable to bacterial monocultivation in microaerotolerant or anaerobic processes with acidic bacteria (either Clostridia or propionic bacteria). Therefore, experiments are conducted in a parallel, gas-tight Multifors bioreactor system.

The polarizability of bacteria is measured by the automated device EloTrace. Feedstock is applied as suggested by LUKE, additional feedstock of higher quality is applied if the polarizability (a kind of cell fitness) is approaching the lower end of the acceptable range. Finally, a methodology for robust processing shall be developed and applied for a period of several weeks. The process is conducted by typical off line measurements for scientific documentation. The product, small molecules like butyric or propionic acid, can then be used as substrate in follow-up bioprocesses. Data of several of such processes is provided to the partners for a thorough LCA and cost evaluation to propose a bio-based strategy for adding value to food waste. This will include data of a currently running process optimization to use fat waste of food production to produce PHA, a biopolymer, with Ralstonia eutropha.

Together with the partners of this project, including the SME Animox, data is provided to other partners to identify a most suitable way to include such a process into food waste streams (both at production and after consumption). The small molecules obtained by the acid fermentation can be used as substrate to produce the polyunsaturated fatty acid docosahexaenoic acid. Such a process was optimized in a BMEL-funded project earlier at TUB. Data of this process is also provided as short chain fatty acids can be used as substrate. Thus, this process rises potential to add value to waste and close carbon circles, if the product (whole cell)