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Marvels that can change our perception of the world

Microorganisms are in the air, on our food, and even in our bodies. Without them we could not even breathe or eat. Billions of microbes live on as well as inside our bodies, enabling and regulating our existence. For every one of our own cells in the body, there may be up to 10 unicellular organisms. One- third of all the metabolic products found in our blood come from bacteria rather than from our own cells. Some researchers even think that a human isn’t an independent creature, but rather a mixture of different organisms— a so-called holobiont. “We are nothing more than a bacterial colony on two legs,” says Jeroen Raes of the Flemish Institute for Biotechnology in Belgium. In just 1 milliliter of intestinal contents, there may be up to 1 trillion bacteria. The various intestinal bacteria fulfill an estimated 15,000 functions, including killing germs, producing vitamins, and strengthening the immune system.