Microbes have taken over the planet. They can even be found in numerous locations throughout the human body. New research has suggested however, that the healthy human bloodstream does not host a stable microbiome. There are microbes that can be found in blood, however, and knowing more about them could help improve the use of donated blood and reduce the risk of infections during transfusion. While this study used samples from healthy individuals, it may one day be possible to use blood microbes as a kind of diagnostic indicator. The findings have been reported in Nature Microbiology.