Microbes Convert Carbon Monoxide and Acetate Into Butyrate in Syngas Fermentation Study

Researchers at Wageningen University & Research showed that mixed microbial communities can convert carbon monoxide and acetate into butyrate, a four-carbon fatty acid used in animal feed, fragrances, and bioplastics. The study, published in Applied Microbiology and Biotechnology, tested three enrichment strategies with different starting inocula. All converged on Eubacterium-dominated communities that produced butyrate under a pure carbon monoxide headspace. That convergence points to carbon monoxide plus acetate as a strong selective pressure for chain elongation. The finding matters for gas fermentation because mixed cultures are more robust than pure strains in industrial reactors. Augmenting sludge with known acetogens shortened the lag phase, which could cut startup costs. Metagenomic data also suggest Eubacterium secretes extracellular polymeric substances that feed other organisms, a form of cross-feeding that may keep the community stable under harsh gas conditions. Butyrate from waste carbon monoxide could fit into a circular carbon economy if the process scales beyond the lab.