Microorganism

microorganismsmicrobemicrobesmicrobialmicro-organismsmicrobial lifemicro-organismgermsgermmicroscopic organisms
A microorganism, or microbe, is a microscopic organism, which may exist in its single-celled form or in a colony of cells.wikipedia
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Microbiology

microbiologistmicrobiologicalbacteriology
Microbiology, the scientific study of microorganisms, began with their observation under the microscope in the 1670s by Antonie van Leeuwenhoek.
Microbiology (from Greek μῑκρος, mīkros, "small"; βίος, bios, "life"; and -λογία, -logia) is the study of microorganisms, those being unicellular (single cell), multicellular (cell colony), or acellular (lacking cells).

Organism

organismsflora and faunaliving organisms
A microorganism, or microbe, is a microscopic organism, which may exist in its single-celled form or in a colony of cells.
Organisms are classified by taxonomy into groups such as multicellular animals, plants, and fungi; or unicellular microorganisms such as protists, bacteria, and archaea.

Archaea

archaeonarcheaarchaebacteria
Of the three domains of life identified by Carl Woese, all of the Archaea and Bacteria are microorganisms.
These microorganisms lack cell nuclei and are therefore prokaryotes.

Bacteria

bacteriumbacterialEubacteria
Of the three domains of life identified by Carl Woese, all of the Archaea and Bacteria are microorganisms.
They constitute a large domain of prokaryotic microorganisms.

Protozoa

protozoanprotozoanspellicle
The third domain Eukaryota includes all multicellular organisms and many unicellular protists and protozoans.
Protozoa (also protozoan, plural protozoans) is an informal term for single-celled eukaryotes, either free-living or parasitic, which feed on organic matter such as other microorganisms or organic tissues and debris.

Human interactions with microbes

Microbes in human cultureMicrobes are important in human culturemicrobes
Microbes are important in human culture and health in many ways, serving to ferment foods, treat sewage, produce fuel, enzymes and other bioactive compounds.
Human interactions with microbes include both practical and symbolic uses of microbes, and negative interactions in the form of human, domestic animal, and crop diseases.

Microbiota

microbiomemicroflorabacterial flora
Microorganisms also make up the microbiota found in and on all multicellular organisms.
Microbiota are "ecological communities of commensal, symbiotic and pathogenic microorganisms" found in and on all multicellular organisms studied to date from plants to animals.

Soil microbiology

component of fertile soilsmicrobiologybiological activity
They are a vital component of fertile soils.
Soil microbiology is the study of microorganisms in soil, their functions, and how they affect soil properties.

Human gastrointestinal microbiota

gut floragut microbiotaintestinal flora
In the human body microorganisms make up the human microbiota including the essential gut flora.
Human gastrointestinal microbiota, also known as gut flora or gut microbiota, are the microorganisms that live in the digestive tracts of humans.

Pathogen

pathogenspathogenicpathogenicity
They are the pathogens responsible for many infectious diseases and as such are the target of hygiene measures.
Typically, the term is used to describe an infectious microorganism or agent, such as a virus, bacterium, protozoan, prion, viroid, or fungus.

Growth medium

mediummediaculture medium
Louis Pasteur (1822–1895) exposed boiled broths to the air, in vessels that contained a filter to prevent particles from passing through to the growth medium, and also in vessels without a filter, but with air allowed in via a curved tube so dust particles would settle and not come in contact with the broth.
A growth medium or culture medium is a solid, liquid or semi-solid designed to support the growth of microorganisms or cells, or small plants like the moss Physcomitrella patens.

Germ theory of disease

germ theorygermsbacteriological revolution
Thus, Pasteur refuted the theory of spontaneous generation and supported the germ theory of disease.
It states that microorganisms known as pathogens or "germs" can lead to disease.

Antonie van Leeuwenhoek

Anton van LeeuwenhoekAntoni van LeeuwenhoekLeeuwenhoek
Microbiology, the scientific study of microorganisms, began with their observation under the microscope in the 1670s by Antonie van Leeuwenhoek.
In the 1670s, he started to explore microbial life with his microscope.

Mold

mouldmoldsfilamentous fungi
Robert Hooke, a contemporary of Leeuwenhoek, also used microscopy to observe microbial life in the form of the fruiting bodies of moulds.
Molds are considered to be microbes and do not form a specific taxonomic or phylogenetic grouping, but can be found in the divisions Zygomycota and Ascomycota.

Koch's postulates

Koch’s postulatesKoch's postulatepostulates
Based on these experiments, he devised criteria for establishing a causal link between a microorganism and a disease and these are now known as Koch's postulates.
Koch's postulates are four criteria designed to establish a causative relationship between a microbe and a disease.

Virus

virusesviralvirion
Beijerinck made two major contributions to microbiology: the discovery of viruses and the development of enrichment culture techniques.
Viruses can infect all types of life forms, from animals and plants to microorganisms, including bacteria and archaea.

Lithotroph

chemolithotrophchemolithoautotrophicchemolithotrophic
Winogradsky was the first to develop the concept of chemolithotrophy and to thereby reveal the essential role played by microorganisms in geochemical processes.
Known chemolithotrophs are exclusively microorganisms; no known macrofauna possesses the ability to use inorganic compounds as energy sources.

Abiogenesis

origin of lifeorigins of lifeformation
Single-celled microorganisms were the first forms of life to develop on Earth, approximately 3–4 billion years ago.
The alternative panspermia hypothesis speculates that microscopic life arose outside Earth by unknown mechanisms, and spread to the early Earth on space dust and meteoroids.

Algae fuel

Algal fuelalgaebiofuel from algae
Microbes are important in human culture and health in many ways, serving to ferment foods, treat sewage, produce fuel, enzymes and other bioactive compounds.
Anaerobic digestion is a straightforward method involved in decomposition of algae into simple components then transforming it into fatty acids using microbes like acidogenic bacteria followed by removing any solid particles and finally adding methanogenic bacteria to release a gas mixture containing methane.

Multiple drug resistance

multidrug resistancemultidrug-resistantmulti-drug resistant
This rapid evolution is important in medicine, as it has led to the development of multidrug resistant pathogenic bacteria, superbugs, that are resistant to antibiotics.
Multiple drug resistance (MDR), multidrug resistance or multiresistance is antimicrobial resistance shown by a species of microorganism to multiple antimicrobial drugs.

Three-domain system

three domainsdomainsthree domains of life
Of the three domains of life identified by Carl Woese, all of the Archaea and Bacteria are microorganisms.
They include many large single-celled organisms and all known non-microscopic organisms.

Enrichment culture

enrichmentenrich
Beijerinck made two major contributions to microbiology: the discovery of viruses and the development of enrichment culture techniques.
Enrichment culture is the use of certain growth media to favor the growth of a particular microorganism over others, enriching a sample for the microorganism of interest.

Motility

motilenonmotilenon-motile
The discovery of microorganisms such as Euglena that did not fit into either the animal or plant kingdoms, since they were photosynthetic like plants, but motile like animals, led to the naming of a third kingdom in the 1860s.
The term applies to bacteria and other microorganisms, and to some multicellular organisms, as well as to some mechanisms of fluid flow in multicellular organs and tissue.

Extremophile

extremophilesextremophilicpolyextremophile
Some are adapted to extremes such as very hot or very cold conditions, others to high pressure and a few such as Deinococcus radiodurans to high radiation environments.
In the 1980s and 1990s, biologists found that microbial life has great flexibility for surviving in extreme environments—niches that are acidic or extraordinarily hot, for example—that would be completely inhospitable to complex organisms.

Animalcule

animalculesanimalcula
The earliest known idea to indicate the possibility of diseases spreading by yet unseen organisms was that of the Roman scholar Marcus Terentius Varro in a 1st-century BC book titled On Agriculture in which he called the unseen creatures animalcules, and warns against locating a homestead near a swamp:
The term was also used in the 17th century by Henry Oldenburg, the first Secretary of the Royal Society and founding editor of Philosophical Transactions, to translate the Dutch words used by Anton van Leeuwenhoek to describe microorganisms that he discovered.