The Microbe World

What are Microbes?             |              Where Do Microbes Live?

Microbes are everywhere - a largely unseen world of living things that support life processes. "The Microbe World" provides a comprehensive directory of micro-organisms and their activities.
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Where Do Microbes Live?

Microbes live in almost every nook and cranny you can think of, from 20 miles beneath the Earth's surface to 20 miles overhead. They live at temperatures less than -20 degrees Celsius to temperatures hotter than the boiling point. Microbes thrive on a huge range of foods including oil and toxic wastes. Every time you walk on the ground you step on billions of microbes. Microbes live in the soil, on rocks, inside roots, buried under miles of Earth, in compost piles and toxic waste, and all over the Earth's surface. Microbes are found in boiling hot springs and on frozen snowfields. Microbes live in homes, in schools and on statues. They live on your cutting board, on your shower curtain, in your couch and in your carpet. Some microbes can survive temperatures about the boiling point. Other microbes live on snow and ice and die at room temperature. Some microbes "breathe" substances other than oxygen such as nitric acid, sulfuric acid, iron, arsenic or uranium to produce energy. Some microbes live near roots of plants in symbiotic associations. Still other microbes flourish in chemical environments harmful to humans and remove toxins like oil and pesticides.

Where there is water, there are microbes. Microbes, like other living organisms, need water to live and reproduce. However, some microbes prefer environments that have more water than the millimeters of water surrounding a particle of soil, or than is found in many foods.

There are many types of watery environments. These range from freshwater ponds, streams, puddles, lakes, rivers, and swamps to salty seas with three times the salt concentration of the ocean. Microbes live in overgrown slime, on pipes and in open oceans with few nutrients to support microbial life. Microbes thrive in streams with lots of oxygen to murky bogs that have no oxygen. In ponds there is a rich thriving ecosystem of microbial life including green and purple bacteria and algae, sulfate reducers, methane producers, and others. Many microbes live in the bottom of lakes and rivers in sediments. Many microbes cannot survive except in the presence of high concentrations of salt.

The largest watery place on earth is the ocean. Oceans cover 71% of the Earth's surface and are responsible for producing about half of the world's organisms, which includes the plants, animals, fungi, and microbes. Most life in the oceans lives at the sunlit ocean surface. Below 25 meters there is little light in the ocean, and life productivity decreases. As well as little light, deeper waters are cooler, which supports less life. Below 50 meters, the temperature is less than 10 degrees Celsius.

Most animals interact with microbes in important ways, and all animals, as well as all plants and fungi, depend on microbes for their survival. Microbes live in their digestive systems, in their mouths, and on their skin. Microbes are important for the good health of animals. Because many animals have more microbe cells than they have animal cells living in or on them, it is as if animals developed as homes for microbes. Animals provide microbes with food and shelter. That is why animals are called "hosts" to microbes. Often when people think about microbes and animals, they think of disease. However, most microbes do animals more good than harm. For example, cows depend on microbes for their food. Cows and other animals called ruminants have special stomachs called rumens which are host to billions of microbes that help these animals survive. Also we depend on microbes to clean up our environment. Without microbes to get rid of all the dung from animals, the world would be a really smelly place. Microbes make this world a cleaner place.

Microbes live in the farthest reaches of the atmosphere. Microbes may inhabit space beyond our world. The air around us is filled with microbes. Bacteria, fungi, algae, protozoa, and viruses float in air currents. The numbers of microbes in the air range from 10 to 10,000 per cubic meter. They are found easily up to 3000 meters and as high as six miles into the air. Microbes may inhabit space beyond our earth. If life exists on other planets, it is most probably microbial life. If we are to ever colonize another planet or moon or go for long space flights, we must build life support systems using the help of microbes. Long term missions in space will require the cooperation of microbes. Microbes can be used to recycle water and nutrients aboard space craft and in extraterrestrial colonies.

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