Ectoine is a valuable raw material for the cosmetics industry and is used in day creams and for UV protection. Its synthesis involves several chemical transformations based on complex raw materials, which makes its production expensive. In the search for simpler raw materials, CO₂ is particularly interesting.
Among the emerging strategies for utilizing CO₂ as a raw material, its electrochemical reduction into fuels and other raw materials has gained significant attention. In an earlier article, we had already reported on our own experiments. One of the easily producible products is formic acid, which can serve as an intermediate for microbial synthesis. This is partly due to the high solubility of formic acid in water, its relatively high purity without many by-products, and the low overpotential during CO₂ reduction.
The microbial synthesis of higher-value products from formic acid has generated increasing interest. This can be achieved, for example, through genetic modifications of Escherichia coli. To combine electrochemical CO₂ reduction with microbial synthesis, other microorganisms such as Cupriavidus necator, Methylobacterium extorquens, and acetic acid bacteria have also been investigated. Usable products have included bioplastics, long-chain carboxylic acids, amino acids, and alcohols.
However, these efforts have largely focused on bulk products or precursors such as acetic acid, ethanol, butanol, polyhydroxyalkanoates, etc. The potential for the synthesis of high-quality products is still vastly underexplored.
Researchers at the Helmholtz Centre for Environmental Research – UFZ in Leipzig (Germany) have now demonstrated the feasibility of producing ectoine from formic acid and published their findings in the journal Engineering in Life Sciences.
They utilized Methyloligella halotolerans, which has the ability to grow using formic acid as its sole energy source. The researchers compared ectoine production using four different substrates: methanol, formic acid, and electrochemically produced formic acid from CO₂.
Thus, the electrochemical reduction of CO₂ on tin-based gas diffusion electrodes was performed prior to biological processing. This resulted in a methanol-formic acid mixture. CO₂ was reduced in a flow cell with a tin-based gas diffusion cathode and a platinum anode. A Nafion 117 proton exchange membrane separated the chambers. Both sides were filled with salt medium to minimize the ionic transition before the direct feeding of the catholyte into the culture.
Moreover, the researchers showed that saline microbiological media could be used as an electrolyte solution for the combined electrochemical-microbial synthesis. This is important because salt solutions have better conductivity.
This study establishes formate as a suitable carbon source for ectoine synthesis in the halophilic methylotrophic bacterium Methyloligella halotolerans. By using electrochemical formic acid for ectoine synthesis, the researchers demonstrated that saline electrolytes can be utilized for the combined electrochemical-microbial synthesis of valuable compounds in electro-biorefining.
Substrate-specific ectoine yields were consistently higher with methanol. A substrate mixture of formic acid and methanol improved the uptake of formic acid but fell short of pure methanol. This underscores the importance of future optimizations for formic acid uptake by microorganisms.
Optimizing electrochemical parameters, including improved buffering, electrolyte composition, and electrode selectivity in saline solutions, could further enhance yields. Additional advancements through strain breeding or genetic modification, better substrate mixtures, and the recovery of ectoine through gentler methods instead of cell lysis could significantly increase productivity.
At Frontis Energy, we are always eager to see how the proposed solution can be scaled industrially and how products like microbial ectoine can be established in markets such as pharmaceuticals and cosmetics.
Kas et al., 2026, Exploring ectoine production from methanol, formate, and electrochemically produced formate by Methyloligella halotolerans, Engineering in Life Sciences, 26:e70063, DOI: 10.1002/elsc.70063
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