A microorganism (also can be spelled as micro organism) or microbe is an organism that is microscopic (too small to be seen by the naked human eye) The study of microorganisms is called microbiology， a subject that began with Anton van Leeuwenhoek's discovery of microorganisms in 1675， using a microscope of his own Microorganisms are incredibly diverse and include bacteria， fungi， archaea， and protists， as well as some microscopic plants and animals such as plankton， and popularly-known animals such as the planarian and the They do not include viruses and prions， which are generally classified as non- Most microorganisms are single-celled， or unicellular， but some multicellular organisms are microscopic， while some unicellular protists， and a bacteria called Thiomargarita namibiensis are visible to the naked Microorganisms live in all parts of the biosphere where there is liquid water， including hot springs， on the ocean floor， high in the atmosphere and deep inside rocks within the Earth's Microorganisms are critical to nutrient recycling in ecosystems as they act as As some microorganisms can fix nitrogen， they are a vital part of the nitrogen cycle， and recent studies indicate that airborne microbes may play a role in precipitation and [1]Microbes are also exploited by people in biotechnology， both in traditional food and beverage preparation， as well as modern technologies based on genetic However， pathogenic microbes are harmful， since they invade and grow within other organisms， causing diseases that kill millions of people， other animals， and 更多请看
