Electro-Enhanced Gas Fermentation for Bioproduction of Volatile Fatty Acids and Alcohols
This study investigates sub-stoichiometric electron supply, also termed electro-fermentation, to influence product formation in gas fermentation. Two species, <i>Clostridium carboxidivorans</i> and <i>Alkalibaculum bacchi</i>, as well as a co-culture of <i>A. bacchi<...
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| Main Authors: | , |
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| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2025-01-01
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| Series: | Microorganisms |
| Subjects: | |
| Online Access: | https://www.mdpi.com/2076-2607/13/2/249 |
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| Summary: | This study investigates sub-stoichiometric electron supply, also termed electro-fermentation, to influence product formation in gas fermentation. Two species, <i>Clostridium carboxidivorans</i> and <i>Alkalibaculum bacchi</i>, as well as a co-culture of <i>A. bacchi</i> and <i>Clostridium kluyveri</i>, were tested in batch cultures with and without an external cell potential of 800 mV. The supplied gas mixture was 50:40:10 N<sub>2</sub>:H<sub>2</sub>:CO<sub>2</sub>. The test unit was a single-chamber reactor with a cathode made from an electrically conducting composite of PP and black carbon. The observed current densities were generally very low, around 0.22 mA/m<sup>2</sup>. Despite that, a significant and reproducible change in product patterns and formation rates occurred. <i>C. carboxidivorans</i> increased the formation of acetate (+32%), butyrate (+300% relative to the control), and caproate (+600% relative to the control). In a similar manner, <i>A. bacchi</i> produced more acetate (+38%), butyrate (13 times more than the control), and caproate (only observed in the electrified setup). Additional trials using a modified gas phase composition, 80:20 H<sub>2</sub>:CO<sub>2</sub>, confirmed the finding that the application of an electric potential enhances chain elongation as well as alcohol formation. Moreover, an experiment with reversed electric polarity showed that a high cathode surface area is essential for inducing metabolic modifications. The results demonstrate that electro-fermentation holds significant potential for improving bioconversion processes aimed at producing green chemicals. |
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| ISSN: | 2076-2607 |