Inside your mouth right now, there is a group of bacteria whose closest relatives can also be found in the belly of a moose, in dogs, cats, and dolphins, and in groundwater deep under the Earth’s surface. In a stunning discovery, scientists have found that these organisms have adapted to these incredibly diverse environments—without radically changing their genomes.
The organisms are members of the TM7, or Sacchraribacteria, phylum. These are ultra-small, parasitic bacteria with small genomes that belong to a larger group called the Candidate Phyla Radiation (CPR). These CPR bacteria are mysterious “dark matter” that represent more than 25 percent of all bacterial diversity, yet we know very little about them since the vast majority remain uncultivated.
In research first published as a pre-print in 2018, and now formally in the journal Cell Reports, scientists describe their findings that Saccharibacteria within a mammalian host are more diverse than ever anticipated. The researchers also discovered that certain members of the bacteria are found in the oral cavity of humans, the guts of other mammals, and in groundwater. While these environments are all very different, the bacteria’s tiny genomes remain minimally changed between humans and groundwater. This indicates that humans acquired the bacteria more recently, on an evolutionary timescale.
Read more at Forsyth Institute
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