Exploration of microbial systems as biocatalysts for conversion of synthesis gas to bio-based chemicals

Synthesis gas (syngas) fermentation is a process capable of processing a gaseous substrate via fermentation into commodity chemicals and fuels. Gas (mainly consisting of hydrogen, carbon monoxide and carbon dioxide) fed to the fermentation process can be obtained from a wide variety of sources, including off-gases from industry, gasification of solid carbon wastes (e.g. municipal waste, lignocellulosic biomass) or gas derived from electrochemical reduction/physicochemical reduction processes. Current limitations of the fermentation process are the relatively poorly understood physiology and genetics of the biocatalysts involved. Therefore the work described in this thesis aimed at unravelling of the syngas metabolism of acetogenic and methanogenic strains, with main focus on carbon monoxide metabolism. In addition, the application of synthetic co-cultures for syngas fermentation was explored in order to assess if such cultivation approach could lead to broadening of the syngas fermentation product spectrum. In addition to co-cultivation proof-of-concept studies for application, new fundamental insights on the metabolism of the involved biocatalysts were obtained.