Cocultivation of clostridia for syngas conversion

(M.Sc. Miriam Bäumler)

Syngases produced as byproducts in many industrial processes or obtained by gasification of organic residues, contain carbon monoxide, carbon dioxide and hydrogen. Usually synthesis gas is used for power generation. An alternative is the conversion of synthesis gases with anaerobic bacteria.

Autotrophic growing acetogenic microorganisms such as Clostridium carboxidivorans are capable of forming organic acids and alcohols from carbon monoxide, with ethanol and acetate as the main products. Economically relevant longer-chain alcohols such as butanol, hexanol or even octanol are only formed in low concentrations from carbon monoxide. There are also known anaerobic bacteria such as Clostridium kluyveri, which can grow solely with acetate and ethanol as carbon sources and thereby form longer-chain organic acids like butyrate, hexanoate and octanoate (chain elongation). Subsequently, bacteria such as Clostridium carboxidivorans should in principle be able to reduce these organic acids in the presence of carbon monoxide to the corresponding alcohols.

The aim of this research project is therefore the establishment of a stable synthetic mixed culture of anaerobic microorganisms such as Clostridium carboxidivorans and Clostridium kluyveri in controlled, continuously gassed bioreactors to enable the bioproduction of longer-chain alcohols from synthesis gas in one reactor.


  • Bäumler M, Burgmaier V, Herrmann F, Mentges J, Schneider M, Ehrenreich A, Liebl W, Weuster-Botz D (2023): Continuous production of ethanol, 1-butanol and 1-hexanol from CO with a synthetic co-culture of Clostridia applying a cascade of stirred-tank bioreactors. Microorganisms 11: 1003.
  • Herzog J, Mook A, Guhl L, Bäumler M, Beck MH, Weuster-Botz D, Bengelsdorf FR, Zeng A-P (2023): Novel synthetic co-culture of Acetobacterium woodii and Clostridium drakei using CO2 and in situ generated H2 for the production of caproic acid via lactic acid. Eng Life Sci 23: e2100169.
  • Mittermeier F, Bäumler M, Arulrajah P, García Lima JJ, Hauke S, Stock A, Weuster-Botz D (2023): Artificial microbial consortia for bioproduction processes. Eng Life Sci 23: e2100152.
  • Bäumler M, Schneider M, Ehrenreich A, Liebl W, Weuster-Botz D (2022): Synthetic co-culture of autotrophic Clostridium carboxidivorans with chain elongating Clostridium kluyveri monitored by flow cytometry. Microb Biotechnol 15: 1471–1485.
  • Schneider M, Bäumler M, Lee NM, Weuster-Botz D, Ehrenreich A, Liebl W (2021): Monitoring co-cultures of Clostridium carboxidivorans and Clostridium kluyveri by fluorescence in situ hybridization with specific 23S rRNA oligonucleotide probes. System Appl Microbiol 44: 126271.