At left,a clump of Staphylococcus epidermidis bacteria in the extracellular matrix, which connects cells and tissue. At right,the bacterium, Enterococcus faecalis, which lives in the human gut, a microbe that will be studied as part of NIH’s Human Microbiome Project. 
    (Photo by NIAID / File / AP) 
    
    
  
  
 
  
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