M e e t Your Microbiome Y ou might think you’re alone but you’re not Ever Wherever you go tiny hitchhikers tag along for the ride Some have been hanging around your body since before you were born and some are climbing aboard right now maybe even from the pages of this book But don’t panic Most of them are harmless The hitchhikers are actually microbes tiny living things so small that you need a microscope to see them And every person carries around trillions and trillions of these critters They are part of what scientists call your microbiome MY-croh-BY-ome A biome is a group of plants animals and other organisms living things that all live in a similar kind of place The tropical rainforest and the arctic tundra are examples of different biomes A microbiome is much the same except the organisms are microscopic and the place is a lot smaller too It might even be a living creature such as a dog a mouse or you 6
Where will you find your collection of microbes Everywhere They’re inside and outside of you in your nose and mouth in your lungs between your toes in your hair and eyelashes and snuggled in the warm hollow behind your ears And a huge number of microbes live in your gut Just as in the rainforest where some kinds of organisms live in the treetops and others down in the tree roots different kinds of microbes settle in the places that suit them best In some ways you might even be more microbe than you are human Scientists estimate that for every human cell in your body there’s at least one microbe cell and maybe as many as ten But those microbes aren’t alien invaders The truth is you need them and they need you Microbes and humans have been together for so long that we depend on each other to survive So in a way microbes are us 7 Did You Know It’s not really possible to count the microbes or the cells in a human body You can only take an educated guess Currently the best guesses place the number of microbes in the average adult human between 100 trillion and 200 trillion That’s a lot If you counted all day and all night every day it would take you more than 3000 years just to get to 100 trillion
W h at Are Microbes M ost of the microscopic organisms traveling in you and on you are just a single cell or something even smaller Some can make you sick and others do little more than hang out and keep you company But plenty of microbes are actually good for you They help you digest food train your immune system to fight disease produce chemicals that keep you healthy or even form protective layers that block other more harmful microbes All microbes are small but that doesn’t mean they’re all the same Here’s a guide to the most common microbial hitchhikers Bacteria bak-TEE-ree-ah These single-celled organisms are found almost everywhere on Earth from deep underground to high in the sky A few are big enough to be seen with the naked eye but the bacteria in your microbiome are much smaller than that In fact several hundred thousand of them would fit on the pointy end of a pin There are more bacteria on Earth than any other kind of organism and they are probably the most common kind of microbe in your microbiome Bacteria Archaea Viruses 8
Archaea ar-KEE-ah This is another group of single-celled organisms but they are not closely related to bacteria Archaea are experts at surviving in tough places one kind can even live in acid strong enough to eat through metal Others though hang out in comfier places such as your belly button Viruses VY-russ-ez Smaller than a cell each one is just a few scraps of genetic code inside a protective coating The virus that causes the common cold contains only 10 genes compared to the 20 000 genes in a human cell Viruses can’t make energy or reproduce on their own Instead they invade a cell and trick it into making copies of the virus Sometimes the copies slip out through the cell wall and go in search of more cells to invade Sometimes the cell just keeps creating viruses until it explodes spreading viruses everywhere What did the criminal virus say to the bacteria I'm gonna bust out of this cell Fungi FUN-jee This group includes everything from single yeast cells to huge mushrooms The fungi in and on your body are the single-celled variety that adore warm damp spots like the spaces between your toes Protists PROH-tists These tiny single-celled relatives of fungi animals and plants are bigger than a lot of other microbes but still microscopic Some protists cause serious diseases but many of them just live with us as part of us Mites Relatives of spiders and scorpions mites are the giants of your microbiome but you still need a microscope to see them They’re especially fond of hair follicles and the oil glands in your skin Fungi Protists 9 Mites
