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LIVING THINGS
| FUNGI |
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One Kingdom of living things is called the
Kingdom Fungi. A fungus (pronounced /'f??g?s/;
pl. fungi)) is a member of a large group
of eukaryotic organisms that includes microorganisms
such as yeasts and molds (or moulds: see
spelling differences), as well as the more
familiar mushrooms. These organisms are classified
as a kingdom, Fungi (pronounced /'f?nd?a?/
or /'f??ga?/), that is separate from plants,
animals and bacteria. One major difference
is that fungal cells have cell walls that
contain chitin, unlike the cell walls of
plants, which contain cellulose. These and
other differences show that the fungi form
a single group of related organisms, named
the Eumycota (true fungi or Eumycetes), that
share a common ancestor (a monophyletic group).
This fungal group is distinct from the structurally
similar myxomycetes (slime molds) and oomycetes
(water molds). The discipline of biology
devoted to the study of fungi is known as
mycology, which is often regarded as a branch
of botany, even though genetic studies have
shown that fungi are more closely related
to animals than to plants.
Abundant worldwide, most fungi are inconspicuous
because of the small size of their structures,
and their cryptic lifestyles in soil, on
dead matter, and as symbionts of plants,
animals, or other fungi. They may become
noticeable when fruiting, either as mushrooms
or molds. Fungi perform an essential role
in the decomposition of organic matter and
have fundamental roles in nutrient cycling
and exchange. They have long been used as
a direct source of food, such as mushrooms
and truffles, as a leavening agent for bread,
and in fermentation of various food products,
such as wine, beer, and soy sauce. Since
the 1940s, fungi have been used for the production
of antibiotics, and, more recently, various
enzymes produced by fungi are used industrially
and in detergents. Fungi are also used as
biological pesticides to control weeds, plant
diseases and insect pests. Many species produce
bioactive compounds called mycotoxins, such
as alkaloids and polyketides, that are toxic
to animals including humans. The fruiting
structures of a few species contain psychotropic
compounds and are consumed recreationally
or in traditional spiritual ceremonies. Fungi
can break down manufactured materials and
buildings, and become significant pathogens
of humans and other animals. Losses of crops
due to fungal diseases (e.g. rice blast disease)
or food spoilage can have a large impact
on human food supplies and local economies.
The fungus kingdom encompasses an enormous
diversity of taxa with varied ecologies,
life cycle strategies, and morphologies ranging
from single-celled aquatic chytrids to large
mushrooms. However, little is known of the
true biodiversity of Kingdom Fungi, which
has been estimated at around 1.5 million
species, with about 5% of these having been
formally classified. Ever since the pioneering
18th and 19th century taxonomical works of
Carl Linnaeus, Christian Hendrik Persoon,
and Elias Magnus Fries, fungi have been classified
according to their morphology (e.g., characteristics
such as spore color or microscopic features)
or physiology. Advances in molecular genetics
have opened the way for DNA analysis to be
incorporated into taxonomy, which has sometimes
challenged the historical groupings based
on morphology and other traits. Phylogenetic
studies published in the last decade have
helped reshape the classification of Kingdom
Fungi, which is divided into one subkingdom,
seven phyla, and ten subphyla.