Production of Medium-Chain Fatty Acids from Syngas by a Bacteria Co-Culture

Synthesis gas, a mixture of CO, H₂, and CO₂, is a promising renewable feedstock for bio-based production of organic chemicals. Production of medium-chain fatty acids can be done via chain elongation using acetate and ethanol, main products of syngas fermentation by acetogens. Therefore, syngas can be indirectly used as a substrate for the chain elongation process.

The team of Martijn Diender from Wageningen University reports the establishment of a synthetic co-culture consisting of Clostridium autoethanogenum and Clostridium kluyveri. Together, these bacteria are able to convert CO and syngas to a mixture of C₄ and C₆ fatty acids and their respective alcohols.

The co-culture is also able to grow using solely CO or syngas as a substrate, and acetate significantly stimulates their production rates. The co-culture produced butyrate and caproate as well as butanol and hexanol. However, pH was found to be a major factor during cultivation, influencing the growth performance of the separate strains and caproate toxicity.

This could be an alternative way to produce medium-chain fatty acids and higher alcohols from carbon monoxide or syngas. The process can also be regarded as an integration of syngas fermentation and chain elongation.