Engineering Acetobacterium woodii for the production of isopropanol and acetone from carbon dioxide and hydrogen

• Published in: Biotechnology journal 2022-05, Vol.17 (5), p.e2100515-n/a
• Main Authors: Arslan, Kübra, Schoch, Teresa, Höfele, Franziska, Herrschaft, Sabrina, Oberlies, Catarina, Bengelsdorf, Frank, Veiga, María C., Dürre, Peter, Kennes, Christian
• Format: Article
• Language: English
• Subjects: Acetobacterium woodii; acetogen; isopropanol; syngas; Wood‐Ljungdahl pathway
• ISSN: 1860-6768; 1860-7314
• DOI: 10.1002/biot.202100515

The capability of four genetically modified Acetobacterium woodii strains for improved production of acetone from CO2 and hydrogen was tested. The acetone biosynthesis pathway was constructed by combining genes from Clostridium acetobutylicum and Clostridium aceticum. Expression of acetone production genes was demonstrated in all strains. In bioreactors with continuous gas supply, all produced acetic acid, acetone, and, surprisingly, isopropanol. The production of isopropanol was caused by an endogenous secondary alcohol dehydrogenase (SADH) activity at low gas‐feeding rate. Although high amounts of the natural end product acetic acid of A. woodii were formed,14.5 mM isopropanol and 7.6 mM acetone were also detected, showing that this is a promising approach for the production of new solvents from C1 gases. The highest acetic acid, acetone, and isopropanol production was detected in the recombinant A. woodii [pJIR750_ac1t1] strain, with final concentrations of 438 mM acetic acid, 7.6 mM acetone, and 14.5 mM isopropanol. The engineered strain A. woodii [pJIR750_ac1t1] was found to be the most promising strain for acetone production from a gas mixture of CO2 and H2 and the formation of isopropanol in A. woodii was shown for the first time. Graphical and Lay Summary For innovative acetone and iso‐propanol production in A. woodii, the modification of the initial plasmid pJIR750_actthlA was the insertion of the native ribosome binding site (RBS) of the acetoacetate decarboxylase (adc) (CA_P0165) and CoA transferase (ctfA) genes (CA_P0163), resulting in plasmid pJIR750_ac1t1. In a continuous stirred tank reactor (STR), gas fermentation was performed with continuous gas supply by using A. woodii pJIR750_ac1t1. At the end of the process 7.6 mM acetone and 14.5 mM acetone was produced.