Your most successful cohabitants are bacteria—microscopic organisms that have only a single cell to their names. Their numbers are overwhelming— you’ll find millions in a drop of saliva and billions in a gram of garden soil. And despite the fact that you’ll never see one (at least not without help from a seriously powerful microscope), they’re easily the world’s most populous life-form. As microbiologists like to say, we are the minority on planet Earth.
Up close, bacteria have a variety of shapes. They may look like tiny spheres, spirals, or—most commonly—stubby rods, like the happy family of E. coli
Bacteria of all kinds cover just about every livable surface in the world around you. In fact, they thrive in a lot of places you probably don’t want them, such as your kitchen silverware. But the part that you really don’t want to think about is that you’re never far from their favorite home—you.
Bacteria colonize your mouth, throat, and eyes. Entire civilizations of exotic life-forms reside on your skin. But most of the bacteria in your body live in the winding passages of your digestive tract. In fact, bacteriologists say that the number of bacteria in your intestines is 10 times greater than the total number of cells that make up your entire body. (Fortunately, bacterial cells are quite a bit smaller than the other cells in your body.) This fact has led some sharp-witted scientists to ask if our bodies are really designed for us, or if we’re just around to serve as a giant luxury hotel for the care and feeding of bacteria.
Bacteria are responsible for many infamous diseases, including anthrax, tetanus, tuberculosis, the Black Plague, and (on a more embarrassing note) syphilis and gonorrhea. Bacteria are also behind most food-borne diseases, including one of the world’s most studied pathogens, E. coli.
Next time you look at your weight on the scale and see a number that’s a shade too high for your liking, remind yourself that bacteria account for a solid 4 pounds of the total.
Source of Information : Oreilly - Your Body Missing Manual