Our Cryo-ET data also sheds light on the biogenesis of M. smithii EVs. The results suggest they form by budding from the cell membrane and get trapped under the peptidoglycan layer before being released through disruptions in the cell wall.

In our study, we show that EVs from Methanobrevibacter smithii — the predominant archaeon in the human gut — harbor proviral DNA and circular extrachromosomal DNA (eccDNA) that encodes key enzymes for methanogenesis, suggesting a potential impact on methane production in the gut.