Demand for biofuels and other biologically derived chemicals is growing worldwide as efforts increase to reduce dependency on fossil fuels and to limit climate change. Thus, there is an urgent need for sustainable, biotechnological processes to cope with the increasing demand by society for food, water and energy. An innovative solution is to use CO2 or other C1 compounds as feedstock and C1-utilising acetogenic bacteria as the process organisms. Acetogenic bacteria efficiently convert C1 compounds such as CO2, CO, formate or methanol to acetate, some acetogens can also produce ethanol. This makes acetogens ideal biocatalysts for a CO2-based bioeconomy. Gas fermentation using acetogenic bacteria and syngas as feedstock has already been demonstrated in two precommercial 100,000 gal/yr. demonstration facilities deployed at industrial sites to produce fuel ethanol from abundant waste gas resources (by LanzaTech); commercial gas fermentation units are currently in design.
In the project "Acetogens" we aim to better understand the metabolism and its regulation in acetogenic bacteria with a focus on Acetobacterium woodii. In particular we have focussed on formate and methanol metabolism and its regulation, on mixotrophy to enhance carbon recovery, on the role of bacterial microcompartments in substrate conversion and the physiology, regulation and application of carbon capture and hydrogen storage by A. woodii as well as a thermophilic species, Thermoanaerobacter kivui. We have also extended our studies to gut acetogens of the genus Blautia to explore their role in health and well-being of humans and in biotechnology.
Our experiments have given a detailed picture of the biochemistry of methanol conversion in different acetogens and on formate metabolism. By metabolic engineering, we could create a superb acetogenic formate-to-acetate production platform. Moreover, we also redirected carbon flow away from acetate to lactate, formate or butyrate by metabolic engineering and we were able to transform A. woodii into an efficient CO oxidizing bacterium. These studies paved the road for the use of formate, methanol and carbon monoxide as acetogenic feedstocks to produce biocommodities. In addition, a main portion of our project was devoted to the development of a biological process for hydrogen production and scavenging using acetogens. We successfully established procedures to use A. woodii and T. kivui as biorefineries to produce hydrogen from formate and to produce formate from hydrogen plus CO2 with unprecedented rates. These studies culminated in the development of a biobattery or hydrogen storage.
