9781422276150

and breaking down of organic compounds. They also help us use the nutrients in the food we eat and make waste from what’s left over. Other bacteria are used for soil enrichment with crops, for food preservation by pickling, and for decomposition of organic wastes in septic tanks or some sewage disposal plants. Some bacteria are also used by scientists in labs to produce medicines and vaccines. Effects of Harmful Bacteria Some bacteria are harmful as they are a cause of several diseases not only to humans but to plants as well. Typhoid, cholera, tuberculosis, pneumonia, and plague are some of the diseases caused due to bacteria. Many of them are infectious. Harmful bacteria can even spoil our food.

Watch this clip for information about how bacteria can make you sick.

SIDEBAR: DID YOU KNOW?

• Penicillin was discovered by Alexander Fleming in 1928. The first antibiotic to be discovered, it was the by-product of a fungus called Penicillium notatum . • There are millions of bacteria in one gram of soil.

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