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Bacteria iconBacteria
Pique Their Interest
Watch the Understanding: Bacteria video for more information.

Did You Know?

No matter where you go on this planet, you'll find bacteria. In the billions of years bacteria have lived on Earth, these tiny survivors have evolved and adapted to every environment. You?ll find bacteria in icy regions, deserts, and rain forests?even places without air. Some live in the extreme environments of active volcanoes and hydrothermal vents on the ocean floor. Bacteria also live in the human body. In fact, the average healthy person is home to a stunning 100 trillion bacteria.

While some bacteria can move on their own, others must be carried from one place to another. Some bacteria rely on ocean tides, rushing rivers, and other moving bodies of water. The bacterium that causes tuberculosis and others travel on currents of air when an infected person coughs, sneezes, or laughs. Bacteria even hitch rides on animals and use magnetism to point themselves in the right direction.

The first antibiotic grew out of a lab mistake. In 1928 British chemist Alexander Fleming found bacteria growing in petri dishes that he forgotten about. Because the dishes were covered with mold and probably contaminated by other microbes, he decided to throw them away?until he saw something peculiar. No bacteria grew wherever mold existed. Fleming soon concluded that the penicillin mold in the dishes had killed the bacteria. Today we use penicillin as a medicine because it kills many kinds of pathogenic bacteria.

To replenish the soil, farmers introduce bacteria by growing peanuts. Legumes, a group of plants that includes peanuts, peas, and beans, have nodules, or bumps, in their roots. Caused by the Rhizobium bacteria, the nodules absorb nitrogen from the soil. They convert it to nitrate and create an essential nutrient that plants can use. This process works so well that farmers often plant legumes in fields every few years to renew nitrogen-depleted soil where other crops have been grown.