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Bacteria, also called germs, are microscopic organisms not visible with the naked eye. Bacteria are everywhere, both inside and outside of your body. Bacteria can live in a variety of environments, from hot water to ice. Some bacteria are good for you, while others can make you sick.
Bacteria are single-celled, or simple, organisms. Though small, bacteria are powerful and complex, and they can survive in extreme conditions. Bacteria have a tough protective coating that boosts their resistance to white blood cells in the body.
Some bacteria have a tail, called a flagellum. The flagellum helps a bacterium to move around. Other bacteria have sticky hair-like appendages that help bacteria them stick to one other, hard surfaces, and human body cells.
There are many bacteria in the human body, especially in the stomach and mouth. Bacteria are found on surfaces and in substances such as water, soil, and food.
Bacteria can be aerobic, anaerobic, or facultative anaerobes. These terms describe how they respond to oxygen. Aerobic bacteria need oxygen to live. Anaerobic bacteria will die around oxygen. Facultative anaerobes function best with oxygen but do not need it.
Some bacteria are good for you, including the bacteria in your digestive system, or gut. These bacteria help to break down food and keep you healthy. Other good bacteria can produce oxygen are used to create antibiotics. Bacteria are used in food production to make yogurt and fermented foods.
The ecosystem relies on bacteria to function properly. For example, bacteria break down dead matter in the environment, like dead leaves, releasing carbon dioxide and nutrients in the process. Without the release of carbon dioxide, plants are unable to grow.
Though there are many more good bacteria than bad, some bacteria are harmful. If you consume or come in contact with harmful bacteria, they may reproduce in your body and release toxins that can damage your body’s tissues and make you feel ill. Harmful bacteria are called pathogenic bacteria because they cause disease and illnesses like strep throat, staph infections, cholera, tuberculosis, and food poisoning.
Written by: Amber Erickson Gabbey
Medically reviewed by George Krucik, MD, MBA
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