Bacteria and the Nitrogen Cycle

Life on Earth would stop if it weren't for bacteria! Even though they are tiny, they play an important role in maintaining balance on the planet. For example, plants use nutrients in the soil, animals eat the plants, waste is eliminated from the animals, the waste becomes soil, and the cycle continues. Bacteria are essential in cycling the nutrients back into the soil for plants to use, and cycling nitrogen back into the atmosphere.

Nitrogen is found everywhere in the world, including animal waste, the atmosphere, and decaying matter. Nitrogen is needed for all kinds of things, including making amino acids, proteins, and genetic material. Nitrogen is the most abundant gas in the atmosphere, and plants love it. However, nitrogen has to be in a certain form for plants to be able to use it. Here's where bacteria come into the picture! Look at the Nitrogen Cycle diagram to see how bacteria help convert nitrogen into a usable form for other organisms. Click on each plus sign for an explanation of the steps involved.

Bacteria as Decomposers

Have you ever seen a dead mammoth lying around anywhere? Why not? North America had thousands of mammoths 20,000 years ago. Where did all of those bodies go? When living things die, bacteria and other organisms, called decomposers, break down the tissues into smaller substances. Eventually, these nutrients are available to other organisms.

As you can see, bacteria maintain homeostasis in an ecosystem by decomposing dead organisms so that the nutrients can continue to be recycled.

Bacteria and Digestion

Another example of how bacteria maintain balance is their presence in the digestive system of certain animals.

Your body has millions of beneficial bacteria that live in your intestines. If they are there, they compete with other microorganisms and prevent "bad" bacteria from reproducing and making you sick. Lactobacillus acidophilus helps your body produce vitamin K, and also helps digest dairy products. Lactobacillus acidophilus can be taken as a probiotic, which is a microorganism introduced into the body for its beneficial qualities. 

There are animals called ruminants (cows, goats, and deer) that depend on the bacteria E.coli to digest their food. Ruminants have a special stomach (rumen) that stores uneaten grasses, like hay. Billions of E. coli live in the animal's rumens. They break down grass and hay into nutrients the animal can absorb into the bloodstream. Without E. coli, these types of animals would not get the nutrition they need.

You've learned how bacteria can be beneficial and play an essential role in keeping balance in both the environment and in humans. Now let's discuss the bad news.

Bacteria can also disrupt homeostasis in your body, and can make you sick. Any substance that causes disease is called a pathogen. Your body reacts to pathogens to try and maintain homeostasis, and certain symptoms will appear as your body tries to get back on track. Your body may try to get rid of the pathogen by causing you to vomit or have diarrhea. Having a fever is common, too. Bacteria are temperature sensitive, so a fever makes your body a less favorable environment.

Directions: Look over the "Overview of Bacterial Infections" chart. It lists common infections caused by bacteria, as well as the most notable bacterial species involved. Click on each plus sign to see symptoms associated with each infection. 

Five Things You Can Do To Prevent Bacterial Infection:

1. Wash your hands often, and scrub for at least 20 seconds.
2. Cover your mouth and nose with a tissue when coughing or sneezing. 
3. Stay at home if you have signs and symptoms of an infection. 
4. Disinfect 'hot zones'. These include the kitchen and bathroom—two rooms that can have a high concentration of bacteria and other infectious agents. 
5.  Be smart about food preparation. Keep counters and other kitchen surfaces clean when preparing meals. Cooked food is safe only after it's been heated to a high enough temperature to kill harmful bacteria.

Directions: Watch Bacteria: The Good, The Bad, The Kinda Gross to review examples of how some microorganisms can be beneficial while others are harmful.