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| “ | …and because there are bred certain minute creatures which cannot be seen by the eyes, which float in the air and enter the body through the mouth and nose and there cause serious diseases.[15] | ” |
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A microorganism or microbe is a living thing (organism) that is too small to be visible to the human eye (microscopic). The study of microorganisms is called microbiology. Microorganisms can be bacteria, fungi, archaea or protists.
Viruses and prions are not called microorganisms because they are classified as non-living. Micro-organisms are often described as single-celled, or unicellular organisms, but there are unicellular protists that are visible to the human eye, and some multicellular species are microscopic.
Microorganisms live almost everywhere on earth where there is liquid water, including hot springs on the ocean floor and deep inside rocks within the earth's crust. Such habitats are lived in by extremophiles.
Microorganisms are critical to nutrient recycling in ecosystems, because they act as decomposers. Because some microorganisms can also take nitrogen out of the air, they are an important part of the nitrogen cycle. Pathogenic, or harmful, microbes can invade other organisms and cause disease.
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There are many types of microorganisms, but there are good ones and bad ones. The good ones feed on things that were once living, such as fallen leaves and dead animals, causing them to breakdown or decay. The decayed materials mix with soil, providing essential nutrients for plants to use. Without this process, the nutrients in the soil would run out. These types of organisms are called decomposers. They are the natural recyclers of living things on our planet. Microbes also help us make some of our foods, such as bread, cheese, yogurt, beer, and wine. They feed on the sugar in grain, fruit, or milk, giving these foods a special texture and taste. [1]
Some microbes, often called germs, can cause illness or disease. Chickenpox, mumps, and measles are caused by the bad microbes.[1] They are infectious diseases. Some microbes can cause food to decay. Moldy bread or fruit, sour milk, and rotten meat are examples of decayed food. If eaten, this rotten food and drink can cause stomach upsets. Other microbes cause tooth decay. [1]You can protect yourself from harmful microbes by storing and preparing food properly, cleaning your teeth, washing your hands, and by avoiding close contact with ill people.[1]
Here are sentences from other pages on Bacteria, which are similar to those in the above article.
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