Methanosaetaceae

Methanosaetaceae is a family of methanogenic archaea within the phylum Euryarchaeota. Members are acetoclastic methanogens, meaning they convert acetate into methane and carbon dioxide as part of their energy metabolism. They are commonly found in anaerobic environments where acetate is present, such as sediments, wetlands, rice paddies, and anaerobic digesters.

The best-known genus in the family is Methanosaeta, with species including Methanosaeta concilii. Taxonomic revisions in the past have led to changes in the classification of some related organisms, with history linking Methanosaeta and previously used genera such as Methanothrix. Overall, the family is characterized by a strong specialization for acetate as a substrate.

Morphology and physiology: Many Methanosaetaceae are filamentous archaea that form long, slender filaments, sometimes networked within aggregates. They are strict anaerobes and typically rely on acetate as their primary carbon and energy source, displaying a high affinity for acetate and growth at low substrate concentrations. They utilize the acetyl‑CoA pathway in the process of methane formation.

Ecology and role: In anaerobic digestion and other anaerobic ecosystems, Methanosaetaceae play a key role in acetoclastic methanogenesis, converting acetate released by fermentative bacteria into methane. Their relative abundance is favored at low acetate concentrations, while at higher acetate levels Methanosarcina species may become more prominent due to broader substrate utilization.

Applications and observation: Understanding Methanosaetaceae is relevant for wastewater treatment and biogas production, where their activity influences methane yield and process stability. Cultivation is difficult, so molecular and genetic approaches are commonly used to monitor their presence and dynamics in bioreactors and natural sediments.