Researchers capture circular intron RNA hopping between microbial species

Scientists observed a circular intron RNA from a predatory bacterium inside the dead cells of another microbe, revealing a new pathway for jumping genes to move across species.

Researchers at the Max Planck Institute for Marine Microbiology have documented a novel route for mobile genetic elements to cross species boundaries. While examining a slow-growing methane-producing community, they focused on the predatory bacterium Candidatus Velamenicoccus archaeovorus, which attacks microbes that convert limonene to methane. Using sensitive RNA probes, they visualized intron RNA in the predator’s active cells and, unexpectedly, in the dead filaments of Methanothrix soehngenii, the world’s most important methane producer.

The intron RNA adopts a circular configuration that shields it from enzymatic breakdown, enabling it to survive in the empty host. This discovery expands the understanding of how jumping genes, traditionally thought to travel inside plasmids or viruses, can also disseminate via stable circular RNA. The study, led by Jens Harder, underscores a new mechanism of horizontal gene transfer that could influence microbial evolution and broader biological processes.