Fungi grow in a wide variety of environments around the globe. Most fungi are terrestrial and are found in all temperate and tropical areas. A few species live in the Arctic and Antarctic regions, usually as part of lichens . Soil rich in organic matter is an ideal habitat for many species, and only a small number of fungi are found in drier areas or in habitats with little or no organic matter. Some fungi are parasites on plants or animals and live on or within their hosts for at least part of their life cycle. Aquatic fungi usually inhabit clean, cool fresh water, though some species are found in slightly brackish water, and a few thrive in highly polluted streams.

yeast

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Q: How do fungi obtain nutrition?

Saprotrophic fungi obtain their food from dead organic material and are ecologically useful decomposers. Parasitic fungi feed on living organisms (usually plants), thus causing disease. To feed, both types of fungi secrete digestive enzymes into the nutritive surface on which they are growing. The enzymes break down carbohydrates and proteins , which are then absorbed through the walls of the hyphae. Some parasitic fungi also produce special absorptive organs called haustoria , to penetrate deeper into the living tissues of the host.

Q: What is a fungal spore?

Nearly all fungi form and release vast quantities of spores as part of their life cycle. Spores are the main reproductive units for fungi and are usually single cells. They may be produced either directly by asexual methods or indirectly by sexual reproduction. Spores are commonly formed by the fragmentation of the mycelium or within specialized structures (sporangia, gametangia, sporophores, etc.). Some spores, especially those of primitive fungi, have flagella and can swim, though most are nonmotile. When a spore lands in a suitable location, it germinates and grows to form a new fungal individual.

fungus

Written and fact-checked by The Editors of Encyclopaedia Britannica

Last Updated: May 8, 2025 • Article History

Key People:: Emile Christian Hansen; Susan L. Lindquist; Edward L. Tatum; Eduard Buchner

Related Topics:: nutritional yeast; Saccharomyces; compressed yeast; baker’s yeast; Torula

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yeast, any of about 1,500 species of single-celled fungi, most of which are in the phylum Ascomycota, only a few being Basidiomycota. Yeasts are found worldwide in soils and on plant surfaces and are especially abundant in sugary mediums such as flower nectar and fruits. There are hundreds of economically important varieties of ascomycete yeasts; the types commonly used in the production of bread, beer, and wine are selected strains of Saccharomyces cerevisiae. Some yeasts are mild to dangerous pathogens of humans and other animals, especially Candida albicans, Histoplasma, and Blastomyces.

Physical description

As fungi, yeasts are eukaryotic organisms. They typically are about 0.075 mm (0.003 inch) in diameter and have many forms, from spherical to egg-shaped to filamentous. Most yeasts reproduce asexually by budding: a small bump protrudes from a parent cell, enlarges, matures, and detaches. A few yeasts reproduce by fission, the parent cell dividing into two equal cells. Torula is a genus of wild yeasts that are imperfect, never forming sexual spores.

Uses

In food manufacture, yeast is used to cause fermentation and leavening. The fungi feed on sugars, producing alcohol (ethanol) and carbon dioxide; in beer and wine manufacture the former is the desired product, in baking it is the latter. In sparkling wines and beer some of the carbon dioxide is retained in the finished beverage. The alcohol produced in bread making is driven off when the dough is baked. The fermentation of wine and sourdough breads is often initiated by naturally occurring yeasts present in air. One yeast cell can ferment approximately its own weight of glucose per hour.

fermentation and distillation process for producing whiskey

fungus

organism

Also known as: Fungi, fungi

Written by Constantine John Alexopoulos, Vernon Ahmadjian•All

Fact-checked by The Editors of Encyclopaedia Britannica

Article History

Plural:: fungi

Key People:: Ferdinand Cohn; Sir William Jackson Hooker; Bernard Ogilvie Dodge; Albert Francis Blakeslee; Heinrich Anton de Bary

Related Topics:: bell morel; horn-of-plenty mushroom; Septobasidium; Roscopoundia; cepe

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How do fungi obtain nutrition?

What is a fungal spore?

Where do fungi grow?

News •

US says it broke up effort to bring toxic fungus to Michigan lab from China • June 3, 2025, 5:18 PM ET (AP)

*Podostroma cornu-damae*Toxic fruiting bodies of the fungus *Podostroma cornu-damae*. The fungus can be confused with edible varities and has been responsible for a number of fatalities in Japan and Korea.

artist's conkArtist's conk (*Ganoderma applanatum*), a bracket fungi. Distributed worldwide, the artist's conk is a wood-decaying fungus that primarily grows on dead or dying trees.

fly agaricThe fly agaric (*Amanita muscaria*) is a poisonous fungus.

fungus, any of about 144,000 known species of organisms of the kingdom Fungi, which includes the yeasts, rusts, smuts, mildews, molds, and mushrooms. There are also many funguslike organisms, including slime molds and oomycetes (water molds), that do not belong to kingdom Fungi but are often called fungi. Many of these funguslike organisms are included in the kingdom Chromista. Fungi are among the most widely distributed organisms on Earth and are of great environmental and medical importance. Many fungi are free-living in soil or water; others form parasitic or symbiotic relationships with plants or animals.

Fungi are eukaryotic organisms; i.e., their cells contain membrane-bound organelles and clearly defined nuclei. Historically, fungi were included in the plant kingdom; however, because fungi lack chlorophyll and are distinguished by unique structural and physiological features (i.e., components of the cell wall and cell membrane), they have been separated from plants. In addition, fungi are clearly distinguished from all other living organisms, including animals, by their principal modes of vegetative growth and nutrient intake. Fungi grow from the tips of filaments (hyphae) that make up the bodies of the organisms (mycelia), and they digest organic matter externally before absorbing it into their mycelia.

porcini mushroomEdible porcini mushrooms (*Boletus edulis*). Porcini mushrooms are widely distributed in the Northern Hemisphere and form symbiotic associations with a number of tree species.

While mushrooms and toadstools (poisonous mushrooms) are by no means the most numerous or economically significant fungi, they are the most easily recognized. The Latin word for mushroom, fungus (plural fungi), has come to stand for the whole group. Similarly, the study of fungi is known as mycology—a broad application of the Greek word for mushroom, mykēs. Fungi other than mushrooms are sometimes collectively called molds, although this term is better restricted to fungi of the sort represented by bread mold. (For information about slime molds, which exhibit features of both the animal and the fungal worlds, see protist.)