Microbe



A microorganism (from the Greek: μικρός, mikros, "small" and ὀργανισμός, organismós, "organism") is a microscopic living organism, which may be a single cell or a multicellular organism. The study of microorganisms is called microbiology, a subject that began on Terra with the discovery of microorganisms in 1674 CE by Antonie van Leeuwenhoek, using a microscope of his own design.

Microorganisms are very diverse and include all the bacteria and archaea and almost all the protozoa. They also include some fungi, algae, and certain animals, such as rotifers. Many macro animals and plants have juvenile stages which are also microorganisms. Some microbiologists also classify viruses (and viroids) as microorganisms, but others consider these as nonliving.

Microorganisms live in every part of the biosphere, including soil, hot springs, "seven miles deep" in the ocean, below the ice of Antarctica, "40 miles high" in the atmosphere and inside rocks far down within the Earth's crust (see also endolith). Microorganisms, under certain conditions, have been observed to thrive in the vacuum of outer space. According to one researcher, "You can find microbes everywhere — they're extremely adaptable to conditions, and survive wherever they are."

Microorganisms are crucial to nutrient recycling in ecosystems as they act as decomposers. As some microorganisms can fix nitrogen, they are a vital part of the nitrogen cycle, and recent studies indicate that airborne microorganisms may play a role in precipitation and weather. Microorganisms are also exploited in biotechnology, both in traditional food and beverage preparation, and in modern technologies based on genetic engineering. A small proportion of microorganisms are pathogenic and cause disease and even death in plants and animals. Microorganisms are often referred to as microbes, but this is usually used in reference to pathogens.

