Systematic discovery of putative bacterial symbionts in ciliate protozoa

Microbial interactions have garnered much attention and are considered central to global processes across ecological and evolutionary time scales. In particular endosymbiosis between single cell protists and prokaryotes is established as the key driver in the ancient evolution of eukaryotic cells and organelles, including mitochondria and plastids, and still today represent a mode of interaction critical to the ecology and evolution of species. In the rumen, the ciliate protozoa community can represent up to 50% of the ruminal microbial biomass and is involved in numerous processes affecting the rumen environment as well as the animal. Like protists inhabiting diverse environments, rumen protozoa are presumed to interact with their prokaryotic neighbors