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What Kinds of Bacteria are on Your Hands?

written by: •edited by: Paul Arnold•updated: 9/22/2009

Gene sequencing technology has just been put to novel use; to detect the types and numbers of bacteria on human hands. The results show that women harbour far more bugs than men.

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    Human hand bacteria

    Our bodies are covered from head to foot with bacteria; millions upon millions of the little critters. Most of the time they are harmless, but sometimes they are not. Now very little is known about how bacteria interact with the human body, so scientists used powerful gene sequencing technology to find out a little more about what kinds of bacteria are on our hands and the surface of our skin. Their results, which were published in the Proceedings of the National Academy of Sciences are truly staggering.

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    Gene sequencing technology and bacteria on your hands

    Gene sequencing of 102 hands by scientists from the University of Colorado at Boulder found that a typical hand harbours many more bacteria than previously thought. The study also concluded that the diversity of bacterial species was much greater on female hands.

    Female hands 332,000 genomes were sequenced which resulted in the identification of 4,700 bacterial species. An average hand is home to about 150 different species. Only 5 species were shared amongst the 51 participants to the study. On average the women in this study had about 50% more bacterial species on their hands than men.

    The researchers gave several possible reasons for this, though these are just working hypotheses at the moment. It could be something to do with pH levels. Men's hands are more acidic than women's and this is generally not a pleasant environment for a bug. Or it could be something to do with hormones or differences in sweat and oil production.

    Another interesting facet of this gene sequencing work was that the scientists found no difference in the diversity of bacteria after hand washing with an anti-bacterial soap. Some species were more abundant, others less so. However, researchers advocate people to continue using anti-bacterial gels, soaps and cleansers.

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    Bacteria and skin health

    This new research is a good foundation for understanding the role skin bacteria play in human health. Some will turn out to be harmful, and it's likely that many more will be completely harmless; they occupy spaces that could be taken up by harmful pathogens. But the work will allow scientists to ask more meaningful questions about the relationship between bacterial communities and human health.

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    Photo Credit

    Released into the public domain by JustCurious