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    Home / Science lessons / Bacteria: Tiny But Tough
    • Bacteria: Tiny But Tough

      Bacteria may be microscopic in size, but they make up for it in sheer number. You have millions of bacteria living on your skin alone, and lots more inside of you! Does that thought give you the creeps? We usually think of bacteria as the harmful germs that make us sick, and while that is often true, there are lots of other things bacteria do that we couldn't live without. Read on for some fascinating facts about bacteria: where they live, how they can harm us, and how they can help us.

      Where They Live

      Where they live is one of the most surprising things about bacteria. The truth is, they live everywhere, even places on earth where we once thought nothing could survive!

      Bacteria coloring the water in a hot spring

      In the heat. The hot springs of Yellowstone National Park contain highly toxic, sometimes boiling water. In this environment, where most living things couldn't survive, bacteria called thermophiles (heat-lovers) thrive. These bacteria are fueled by hydrogen and sulfur in the water, and they produce many of the brilliant colors in Yellowstone's hot springs.

      Other thermophiles live near hydrothermal vents on the ocean floor. These vents are usually more than 7,000 ft (1.3 miles) below the surface, and at this depth the water pressure is extreme — it would crush us in no time at all! In addition, the temperature fluctuates drastically between hot vent water pouring out from cracks in the ocean floor and cold sea water. There is no natural light that deep in the sea, and the water spouting from the vents is full of harsh chemicals and minerals. And yet bacteria live there, and even help other creatures (like tubeworms) live by converting the toxic chemicals from the vents into food for them.

      In the cold. Most bacteria don't grow as well in colder temperatures, which is why putting your food in the refrigerator helps keep it from spoiling. There are bacteria called psychrophiles (cold-lovers), though, that can live and reproduce in cold temperatures — even below the freezing point. Researchers in Antarctica have discovered bacteria in ice samples taken from about 11,700 feet deep in the ice above Lake Vostok.

      In radioactive environments. One type of bacteria, called Dienococcus radiodurans, can survive lethal amounts of radiation, up to 1000 times more than would kill a human!

      Inside you. Bacteria live on your skin, on your teeth, on your tongue, in your intestines, in your eyes, and more. You are host to millions of them! Some of them can harm you, but many of them help you. How? Keep reading to find out! But first: what exactly are bacteria?

      What They Are

      Bacteria are one-celled or unicellular microorganisms. They are different from plant and animal cells because they don't have a distinct, membrane-enclosed nucleus containing genetic material. Instead, their DNA floats in a tangle in the interior of the cell. Individual bacteria can only be seen with a microscope, but they reproduce so rapidly that they often form colonies that we can see. Bacteria reproduce when one cell splits into two cells in a process called binary fission. Fission occurs rapidly in as little as 20 minutes. Under perfect conditions a single bacterium could grow into over one billion bacteria in only 10 hours! (It's a good thing natural conditions are rarely perfect, or the earth would be buried in bacteria!)

      How They Can Harm Us

      Disease-causing bacteria are called pathogenic. These come in many forms and can cause illnesses from an ear infection to strep throat to cholera. They can get into our bodies via our mouth and nose, or through cuts and scrapes. Some are airborne, others are found in food, resulting in food poisoning. Bacteria are also the cause of plaque buildup on our teeth, which can lead to cavities and gum disease.

      Before the discovery of antibiotics, many severe bacterial diseases had no cure and usually resulted in death. Antibiotics work by destroying bacteria or inhibiting their reproduction while leaving the body's own cells unharmed. After a time, some bacteria develop resistance to an antibiotic, and it will no longer be effective against them. Because of this, scientists are always researching new antibiotics. (Many diseases, such as chicken pox, hepatitis, or polio, are caused by viruses rather than bacteria. Antibiotics have no effect against these diseases.)

      Bacterial infections are common, but many of them can be avoided by good cooking, cleaning, and hand-washing practices.

      How They Can Help Us

      Where would we be without bacteria? Well, we might not be getting bacterial diseases, but we would still be a lot worse off! Bacteria perform all sorts of very important functions, both in our bodies and in the world around us. Here are just a few.

      Digestion. Our large intestines are full of beneficial bacteria that break down food that our bodies can't digest on their own. Once the bacteria break it down, our intestines are able to absorb it, giving us more nutrients from our food.

      Vitamins. Bacteria in our intestines actually produce and secrete vitamins that are important for our health! For example, E. coli bacteria in our intestines are a major source of vitamin K. (Most E. coli is good for us, but there is a harmful type that causes food poisoning.)

      Food. Bacteria are used to turn milk into yogurt, cheese, and other dairy products.

      Oxygen. Cyanobacteria (which used to be called blue-green algae) live in water and perform photosynthesis, which results in the production of much of the oxygen we need to breathe.

      Cleanup. Oil spills, sewage, industrial waste — bacteria can help us clean all of these up! They 'eat' the oil or toxins and convert them into less harmful substances.

      Bacteria are amazing creatures, aren't they? They can be so dangerous and yet so important at the same time. Since they are everywhere, you can easily experiment with them yourself, even without a microscope. Try it out with this bacteria science project.

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