photo by IRRI Images
Bacteria literally have us covered, inside and out. NIH researchers have found that the healthy human epidermis is home to about 1000 species of bacteria, or an estimated 100 billion individual bacteria total. Various regions of skin from 10 volunteers (5 female, 5 male) were swabbed to collect bacterial samples for analysis. The study found that moist areas housed 10 times more bacteria than dry areas. The human forearm alone showed the greatest bacterial diversity with 44 species detected, while the oily area behind the ear had only 15 species. Interestingly, similar species were found in the same areas on each individual, indicating that bacterial species have their own niche on our skin as well as pointing to a mutualistic relationship between "us" and "them".
Source: Karen Kaplan, "1000 Species of Bacteria Found on Healthy Humans", Los Angeles Times, May 29, 2009.
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