Writing in Nature Microbiology, Tiantian Yu, Shujian Yuan, Yinzhao Wang, Fengping Wang and colleagues report the enrichment of a heat-loving archaeon that appears capable of converting long-chain fatty acids directly into methane without bacterial partners. The organism, provisionally named Candidatus Methanoglobus sphaerolipidus DLY3, belongs to the class Archaeoglobi, a group of thermophilic archaea better known for sulfate reduction than for making methane. Through a combination of selective enrichment, growth experiments, microscopy, stable isotope tracing, metagenomics and metatranscriptomics, the team assembled a case that this single archaeon can ingest fatty substrates such as oleic acid and exhale methane, executing every step of the transformation on its own.

The metabolic itinerary the researchers propose is remarkable in its completeness. Ca. M. sphaerolipidus deploys the beta-oxidation pathway, the same enzymatic assembly line that mitochondria and many bacteria use to clip two-carbon units from fatty acid chains, to break long hydrocarbon tails into smaller fragments. Those fragments are then funneled into the Wood–Ljungdahl pathway, an ancient carbon-fixation route that channels one-carbon compounds toward the central metabolism of the cell. Finally, the reaction is completed by methyl-coenzyme M reductase, or MCR, the nickel-containing enzyme that sits at the heart of all biological methane production, together with methyltransferase complexes that shuffle methyl groups into the methanogenic pipeline. The authors have dubbed this full sequence liparotrophy, from the Greek word for fat.

The mechanistic significance of this finding is hard to overstate. Until recently, the known routes to methane were limited to a handful of well-characterized modes: reduction of carbon dioxide with hydrogen, the acetoclastic split of acetate, methylotrophic fermentation of methylated compounds, methyl reduction, methoxydotrophic use of methoxylated aromatics and, more recently, alkylotrophy, in which archaea activate short-chain alkanes through alkyl-coenzyme M intermediates. Each new mode has expanded the roster of substrates that biology can convert into the most reduced form of carbon. Liparotrophy now adds long-chain fatty acids—abundant, energy-dense molecules that pervade sediments, petroleum reservoirs and anaerobic digesters—to that list, and it does so with a single organism rather than a consortium.

The evidence base for the claim is layered. In enrichment cultures fed oleic acid, methane accumulated while Ca. M. sphaerolipidus rose to dominance in the community, a pattern consistent with the archaeon being the active methane producer. Stable isotope tracing confirmed that carbon from the labeled fatty acid substrate ended up in the methane, directly linking the lipid feedstock to the gaseous product. Microscopy, including hybridization-based fluorescent probing and transmission electron microscopy, revealed the morphology and identity of the enriched archaeal cells. And metagenomic and metatranscriptomic sequencing showed not only that the genome of Ca. M. sphaerolipidus encodes the full beta-oxidation, Wood–Ljungdahl and methanogenesis machinery, but that the relevant genes are actively transcribed when fatty acids are on the menu.

Perhaps equally intriguing is the organism’s dietary flexibility. Beyond oleic acid, the enrichment cultures also produced methane when supplied with methanol, a one-carbon alcohol. That versatility places Ca. M. sphaerolipidus within a growing group of Archaeoglobi that blur the line between canonical methanogens and their metabolically adventurous relatives. Recent years have seen methanogenesis or MCR-linked metabolism documented in unexpected corners of the archaeal domain, from Korarchaeia and Methanonezhaarchaeia in the phylum Thermoproteota to nontraditional MCR-bearing lineages in geothermal springs. The new finding reinforces the emerging picture that methane metabolism is far more phylogenetically widespread, and far more biochemically inventive, than the classical methanogen textbooks implied.

Evolutionarily, liparotrophy adds weight to the hypothesis that archaeal alkane and fatty acid metabolism share deep roots. Comparative work has suggested that methylotrophic methanogenesis may represent an ancient origin of the pathway, with the enzymes that activate and cleave carbon–carbon bonds in hydrocarbons diversifying from related alkyl-coenzyme M chemistry. If Archaeoglobi—one of the earliest diverging archaeal lineages—can strip two-carbon units from fatty acids and terminate them in methane via MCR, then the capacity for anaerobic lipid degradation may be far older and more broadly distributed than the syntrophic bacteria-archaea partnerships that dominate anaerobic environments today. The phylogenomic analyses in the new study, which place the MCR and ACR protein families of Ca. Methanoglobus within the broader family tree of methane-related reductases, will help researchers trace how these enzymatic modules were assembled, shuffled and repurposed across billions of years.

The discovery also carries practical weight. Long-chain fatty acids are notorious bottlenecks in anaerobic digestion, the biotechnology that turns food waste, sewage sludge and lipid-rich dairy effluent into biogas. Because fatty acids inhibit the syntrophic consortia that normally process them, high-lipid feedstocks can destabilize digesters and depress methane yields. A thermophilic archaeon that can directly convert these compounds to methane, without the metabolic hand-offs that make conventional syntrophy fragile, could point toward more robust biogas systems for greasy wastes. The thermophilic nature of the organism is a good fit for the elevated temperatures of industrial digesters, and its capacity to switch between fatty acids and methanol suggests metabolic flexibility that engineers could exploit.

Geologically, the implications reach into the deep subsurface. Fatty acids derived from dead biomass are abundant in anoxic sediments, hydrothermal systems and petroleum-associated environments, and the methanogenic degradation of these compounds has long been invoked to explain methane generation in oil reservoirs and coal beds. If liparotrophic archaea are active players in those settings, the microbial routes and rates of subsurface methane production may need revision, with consequences for models of the global methane budget and for understanding where biogenic natural gas comes from. The Tengchong hot springs that yielded DLY3 are just one terrestrial geothermal system; related Ca. Methanoglobus genomes have now been recovered from various thermal environments, hinting that liparotrophy may be a hidden but common metabolism wherever heat and lipids meet.

As with any single-organism claim emerging from enrichment cultures, confirmation will matter. Ca. M. sphaerolipidus has not yet been isolated in pure culture, and the authors make their cultures available to other researchers under material transfer agreements precisely so the wider community can test, refine and extend the findings. But the convergence of isotope data, gene expression profiles and growth behavior makes a compelling case that the boundaries of methanogenesis have just been redrawn once again. A few years ago, methane was the exclusive business of a specialized few; today, it is increasingly clear that across the archaeal tree, evolution has repeatedly found ways to breathe out this simplest of hydrocarbons—and now, it seems, straight from the fats of the dead into the gas of the future.

Subject of Research: Direct methanogenic conversion of long-chain fatty acids by thermophilic Archaeoglobi

Article Title: Evidence of direct methane production from long-chain fatty acids by thermophilic Archaeoglobi

Article References: Yu, T., Yuan, S., Wang, Y., & Wang, F. (2026). Evidence of direct methane production from long-chain fatty acids by thermophilic Archaeoglobi. Nature Microbiology. https://doi.org/10.1038/s41564-026-02490-5

Image Credits: AI Generated

DOI: 10.1038/s41564-026-02490-5

Keywords: methanogenesis, Archaeoglobi, long-chain fatty acids, liparotrophy, beta-oxidation, Wood–Ljungdahl pathway, methyl-coenzyme M reductase, thermophiles, hot springs, metagenomics, anaerobic digestion, archaea