Chain elongation to C8. Exploring microbiomes to produce chemical building blocks

Abstract

Die Dissertation ist gesperrt bis zum 22. Mai 2028 !

Next to renewable electric energy, carbon based chemicals must be produced sustainably and independently from fossil sources. To meet this goal, we must expand the portfolio of bio based conversion technologies on an industrial scale to cover as many target chemicals as possible. The bioprocess chain elongation provides medium chain carboxylates that can function as future platform chemicals in the circular bioeconomy. Until now, the most valuable medium chain carboxylate produced via chain elongation is n caprylate (i.e., n octanoate). This molecule, which has eight carbon atoms in a row, is challenging to produce renewably for the chemical industry. Previous studies elucidated that elevated ethanol to acetate ratios, which are found in syngas fermentation effluent, stimulated n caprylate production with open culture bioreactors. While the bioreactor setup and the substrate feeding regime with open-culture microbiomes were already established on a lab scale, the underlying metabolic pathways, and key microbial species responsible for n-caprylate production are not understood. During my work, I focused on examining the process of microbial n caprylate production in greater detail. I operated and analyzed n caprylate producing open-culture bioreactors in search of a mechanism that allows its production with microbial communities. Additionally, I isolated microbial species from these bioreactors. I phyiologically investigated the chain elongating bacterium Caproiciproducens sp. NJN-50 to get a better understanding of the reverse ß-oxidation pathway. The results of my work will help perform more targeted research on ethanol based n caprylate production in the future and sheds light on the metabolic principles of chain elongating bacteria.