Atlant’s Column: The Navel of the Bacterial World

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Welcome to the section on which explores, analyzes and explains fascinating microscopical structures.

Belly Button MicrobesThe belly button is a forgotten part of the human body. Scientists ventured into it in the search for life and found it thousandfold. 

When was the last time you washed your belly button? Yesterday, last week, last month, last year, never in your life? Stop! Before you run to the bathroom to the catch up with cleaning, think for a moment about the treasure you are carrying around with you.

US researchers have recently investigated the bacterial diversity in the navels of 60 volunteers and have discovered over two thousand different types of bacteria. In the navels of two individuals, who have neither bathed nor showered for several years, they even found representatives of the Archaea .
These types of bacteria occur otherwise only in extreme habitats such as the edges of volcanoes or in acidic lakes.

Belly Button MicrobesThis image shows the diversity of microbes that you may carry around in this small, often forgotten place of your body. On average, every navel harbours 67 different species on average. Some belly buttons are cleaner than others, and contain only 29 different species.


Whether this is better for you is questionable, because the microbes are not just squatters, but they defend us against unpleasant guests. For instance, Bacillus subtilis, which frequently occurs in navels, produces antibiotics. With this weapon it fights other more nasty bacteria but also fungi. This way, it ensures that we are not eaten alive by an armada of microbes. Thus, the biodiversity definitely has a benefit for us – think about it before you sterilize your navel with soap.

Belly Button MicrobesThis snapshot shows more than a dozen different species. But just by their appearance it is not possible to identify them down to the species level, because many bacteria look the same. An exact identification is only possible by means of a genetic fingerprint. On the other hand, it could also be that there are several unnamed bacteria in this image, which haven’t been discovered yet.



More than two weeks of net working time for each picture!

Producing this picture was a big effort for Martin Oeggerli. He had to colorize each bacterium individually by hand. For this step alone he Belly Button Microbesneeded 25 hours. Some weeks before, he spent days sampling a navel with a cotton swab, fixing the probe, dehydrating it, coating it with gold (sample preparation) and finally analyzing the sample and taking black-and-white shots of the bacteria under the scanning electron microscope.




Further reading:

Body map of bacterial biodiversity

Video on how bacteria on your skin communicate with each other


Lesen Sie diesen Artikel auf Deutsch.

Continue reading Atlant’s Column: The More Harmless Mosquito , March 2014, or go back to the archive