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Sustainable bio-based 1,3-propanediol production from C5/C3 sources by metabolically engineered clostridia

Grant number: 18/12471-1
Support type:Regular Research Grants
Duration: May 01, 2019 - April 30, 2022
Field of knowledge:Biological Sciences - Biochemistry
Cooperation agreement: Federal Ministry of Education and Research, Germany
Principal Investigator:Valeria Reginatto Spiller
Grantee:Valeria Reginatto Spiller
Principal investigator abroad: Hans-Peter Karl Heinrich Duerre
Institution abroad: Ulm University, Germany
Home Institution: Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto (FFCLRP). Universidade de São Paulo (USP). Ribeirão Preto , SP, Brazil
Assoc. researchers:Adalgisa Rodrigues de Andrade ; Richard John Ward

Abstract

The joint research proposal focuses on a sustainable, bio-based production of the important commodity chemical 1,3-propanediol (PDO) by anaerobic bacteria of the genus Clostridium. PDO can be manufactured by chemical synthesis or fermentation. Currently, ~150000 t of PDO are produced per year, which is expected to increase to ~225000 t per year by 2022. The joint research proposal is based on two renewable feedstock streams; the C5 fraction of lignocellulose hydrolysis and the glycerol waste fraction of biodiesel production. Both are produced in large quantities in both Germany and the State of São Paulo, Brasil, during biodiesel production and lignocellulose hydrolysis in biorefineries. Thus, the project addresses several of the research topics of the Call, namely development of sustainable bioproducts, use/processing of sustainably produced biomass to make biobased products, and reducing waste from food production.The use of two different bio-based feedstocks will allow growth of the bacteria on pentoses (C5) with production of surplus reducing equivalents, which are used to complete conversion of glycerol to PDO. The eficiency of current glycerol fermentation pathways are limited by the fact that 50% of the glycerol needs to be oxidized in order to produce NADH, which is required for the reduction of the other 50% to PDO. Thus, the use of the C5 stream for growth and NADH production will lead to a much higher glycerol conversion to PDO. This will be achieved by constructing Clostridium mutants that can no longer use reducing equivalents by inactivating the respective genes for alcohols, hydrogen, isopropanol, and lactate production. Fermentation experiments will identify the best feedstock sources and whether simultaneous use of pentoses and glycerol will be hampered by catabolite repression. In the latter case, targeted mutagenesis will be employed to inactivate the responsible regulator CcpA. The clostridia envisaged for this project employ a vitamin B12-independent glycerol dehydratase, and the joint proposal also aims to engineer and express a vitamin B12-dependent glycerol dehydratase from Klebsiella pneumoniae in order to further improve its activity. Finally, we will also address a future use of renewable energy by employing bioelectrochemistry. Thus, we will test whether solar-, wind-, or water-generated electricity can be used as source of reducing equivalents for glycerol reduction to PDO. Clostridial wild-type and recombinant strains will be immobilized on electrodes and the biofilms will tested for uptake and use of the supplied electrons to produce PDO, by electrofermentation in a Microbial Electrolytic Cell (MEC).The joint research proposal will be complemented by graduate student recruitment and exchange programs that will be funded from existing intramural programs, and will therefore not drain the financial resources of the Call. (AU)