Earthworm symbiont Verminephrobacter eiseniae mediates natural transformation within host egg capsules using type IV pili.

The dense microbial communities commonly associated with plants and animals should offer many opportunities for horizontal gene transfer through described mechanisms of DNA exchange including natural transformation (NT). However, studies of the significance of NT have focused primarily on pathogens. The study presented here demonstrates highly efficient DNA exchange by NT in a common symbiont of earthworms.

Verminephrobacter eiseniae type IV pili and flagella are required to colonize earthworm nephridia.

The bacterial symbiont Verminephrobacter eiseniae colonizes nephridia, the excretory organs, of the lumbricid earthworm Eisenia fetida. E. fetida transfers V.