Coproduction of 1,3-propanediol and 3-hydroxypropionic acid from glycerol by Clostridium pasteurianum

• Applicant: Dr. Kai Schuchmann
• Subject Area: Metabolism, Biochemistry and Genetics of Microorganisms
• Term: from 2016 to 2017
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 290250425

Human-caused CO2 emissions predominantly caused by the combustion of fossil fuels is leading to increased atmospheric CO2 concentrations. Rising environmental concerns and uncertainties regarding the climate changes and the inevitable limitation of these fuels necessitate the development of alternative, sustainable routes to fuels and chemical production. Developments of biological alternatives have been mainly focused on sugar-based fermentations. However, these processes suffer from the cost of the edible feedstock. One alternative less expensive feedstock is raw glycerol, the primary by-product of biodiesel production. Growth of the biodiesel economy led to a significant decrease of the price of this feedstock. Disposal of this by-product is a severe burden for biodiesel companies. Utilization of glycerol would improve the recovery of valuable products from the feedstock and benefit biodiesel production by lowering the price of the product. One promising candidate for glycerol utilization is the strictly anaerobic bacterium Clostridium pasteurianum. Bacteria of the genus Clostridium have tremendous advantages over classic model organisms such as Saccharomyces cerevisiae or Escherichia coli with respect to flexibility of substrates utilized and tolerance to toxic compounds. However, sophisticated genetic tools for study and modification of these organisms have just started to become available. C. pasteurianum naturally produces as end-product from glycerol 1,3-propanediol (1,3-PD), an industrially valuable chemical intermediate that can be used, for example, for the synthesis of polymers such as polyesters. Metabolic constraints lead to inevitable by-product formation when 1,3-PD is produced from glycerol to provide necessary reducing equivalents. Changing these natural low value by-products to a more desirable such as 3-hydroypropionic acid (3-HP) can drastically lower the price of the product. 3-HP is a promising C3 building block for the synthesis of commodity as well as specialty chemicals and can be reduced to 1,3-PD. The proposed project aims at the metabolic engineering of C. pasteurianum for the coproduction of 1,3-PD and 3-HP from glycerol. Therefore, a heterologous pathway leading to 3-HP will be introduced and the native pathway to 1,3-PD will be fostered. Furthermore, genetic modifications will prevent the formation of unwanted side products. This sustainable process will employ the cheap and abundant feedstock glycerol and generate important chemical building blocks and will hopefully help to improve and support biodiesel production. The project will not only lead to a desirable biological conversion for the production of valuable chemicals but will hopefully lead to improvements and advances of the so far underdeveloped genetic tools for bacteria of the industrially and medically important genus Clostridium. It will also improve the understanding of the metabolism.

• DFG Programme: Research Fellowships
• International Connection: United Kingdom
• Host: Professor Dr. Nigel P. Minton