are made with certain types of bacteria. Some important drugs
like insulin are made with the help of bacteria. Sewage treatment
plants use bacteria to break down waste products. Other bacteria
are used in mining and to clean up oil spills. There is a good
chance that you’ve benefited from bacteria today!
Symbiosis Many kinds of bacteria have developed close relationships with
other organisms. In many relationships the bacteria and the
organism it lives with benefit. This type of symbiosis is called
mutualism. One species of bacteria lives in your intestines. You
provide the bacteria with a warm, safe place to live. In return, the
bacteria help you break down and absorb certain compounds in
foods. Bacteria even make some vitamins that your cells cannot
make on their own.
Life on Earth
depends on
bacteria
Bacteria are an important part of the nutrient cycles that all life
depends upon. For example, plants need nitrogen to make amino
acids, the building blocks of protein. Bacteria in the soil take
nitrogen out of the air and turn it into a form plants can use. When
animals eat plants, they rearrange the amino acids into other
proteins. When an organism dies, bacteria break down the dead
material and turn it back into compounds that living things can
use again (Figure 9.10). Bacteria are “nature’s recyclers.”
Bacteria and
antibiotics
Have you ever had a bacterial infection? If so, you’ve experienced
one of the harmful effects of bacteria. Bacteria cause diseases like
strep throat, respiratory infections, and infected wounds. Bacterial
diseases are treated with drugs called antibiotics. Antibiotics kill
bacteria without harming your own cells. Different antibiotics are
used for fighting different types of bacteria.