A clump of Staphylococcus epidermidis bacteria (green) in the extracellular matrix is seen at left in an image taken with a scanning electron microscope.
A clump of Staphylococcus epidermidis bacteria (green) in the extracellular matrix is seen at left in an image taken with a scanning electron microscope. At right is a microscopic view of the bacterium Enterococcus faecalis, which lives in the human gut and is just one type of microbe that will be studied as part of NIH's Human Microbiome Project. (AP Photo/NIAID, Agriculture Department)