(DFG funded from 2020 till 2023)
 
This project brought together the complementary expertise of two academic groups specializing in microbiology and molecular biology (Dr. F.R. Bengelsdorf, UULM) and bioprocess engineering/systems biology (Prof. A.-P. Zeng, TUHH). The aim was to generate quantitative and fundamental insights into synthetic co-cultures capable of producing caproate via lactate from CO₂ and H₂. During the project, Acetobacterium woodii mutants were constructed to autotrophically produce lactate (Mook et al., 2022), which was then converted to caproate by Clostridium drakei SL1T, chosen as the second partner for the co-culture (Mook et al., 2024). The compatibility of these strains for the co-culture was examined in terms of growth physiology, including optimal pH, temperature, nutrient requirements, and growth effects. Metabolic interactions were studied in detail, focusing on cell growth kinetics, substrate consumption, and product formation. For cell population quantification, metabolic engineering approaches were employed to generate A. woodii mutants expressing a fluorogenic protein tag, enabling distinction between species and quantification using fluorescence-based flow cytometry. Integrated biomolecular and bioprocess engineering methods were collaboratively applied to optimize co-culture performance for bioprocess development (Herzog et al., 2022; Herzog et al., 2023). In summary, the project addressed key scientific questions related to developing efficient co-culture technologies for producing value-added products such as lactate and caproate from CO₂ and renewable electricity. Several methodological and technological innovations were realized, which could be applied to related processes. 
 
 

 

Herzog J, Mook A, Guhl L, Bäumler M, Beck MH, Weuster‐Botz D, Bengelsdorf FR, Zeng AP (2022). 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. Engineering in Life Sciences, 23, e2100169 . Doi: 10.1002/elsc.202100169.

Herzog J, Mook A, Utesch T, Bengelsdorf FR, Zeng, A-P (2023). Lactate based caproate production with Clostridium drakei and process control of Acetobacterium woodii via lactate dependent in situ electrolysis. Frontiers in Bioengineering and Biotechnology, 11. Doi: 10.3389/fbioe.2023.1212044.

Mook A, Beck MH, Baker JP, Minton NP, Dürre P, Bengelsdorf FR (2022). Autotrophic lactate production from H₂ + CO₂ using recombinant and fluorescent FAST-tagged Acetobacterium woodii strains. Applied Microbiology and Biotechnolology 106: 1447–1458. Doi: 10.1007/s00253-022-11770-z.

Mook A, Herzog J, Walther P, Dürre P, & Bengelsdorf FR (2024). Lactate-mediated mixotrophic co-cultivation of Clostridium drakei and recombinant Acetobacterium woodii for autotrophic production of volatile fatty acids. Microbial Cell Factories, 23, 213. Doi: 10.1186/s12934-024-02481-3.