Types, Morphology & Structure, Uses and Disadvantages
Fungi belong to their own kingdom (Kingdom
Fungi). Compared to higher plants and animals, they obtain their nutrition
through a range of ways including degradation of organic material and
symbiosis (as lichen) among others. As such, they are categorized as
heterotrophic because they are unable to synthesize their own food (they lack
chlorophyll). They can reproduce sexually or asexually with a majority of
fungi being spore producers.
Types of Fungi
The different types may be described
based on their phylum.
Also referred to as Sac Fungi, phylum Ascomycota
is the largest phylum (makes up about 75 percent) of the Kingdom Fungi
with well over 60,000 species of organisms.
Organisms that are grouped under
this phylum are collectively known as ascomycetes including yeast (single
celled organisms) and other filamentous fungi (hyphal). Whereas some are saprobes, others live as parasites while some form symbiotic
relationships with other organisms to survive.
In phylum Ascomycota, the ascus
(sac) is the defining trait. This is the site of nuclear fusion in which
division takes place during reproduction. For most part, this phylum is
composed of heterotroph organisms that obtain nutritional energy from other
organisms (living or dead) as well as other organic compounds.
Some of the
organisms in this phylum are also capable of forming a symbiotic relationship
with other organisms like algae and arthropods for their survival. With regards
to reproduction, Ascomycota reproduce sexually or asexually. Sexually, they
reproduce through the production of spores and the production of mitospores
during asexually reproduction.
being the largest phylum, organisms that fall in this category are also divided
into the following sub-phyla:
Taphrinomycotina - Studies have shown this
sub-phylum (Taphrinomycotina) to be highly diverse. One of the unique traits
associated with Taphrinomycotina is the absence of ascogenous hyphae.
Some of the organisms in this group
include yeast (that produce through binary fission) and Taphria (plant
parasitic) that exist as yeast and hypha among others. Some of the organisms in
this classification are capable of producing fruiting bodies known as ascomata.
These fall in the species known as Neolectomycetes.
Saccharomycotina - Most of the organisms
(yeast) that fall under this sub-phylum are saprotrophs. The sub-phylum also
contains a number of parasitic organisms that tend to be pathogenic. Studies
have shown these organisms to largely reproduce through the formation of naked
asci (cells that produce spores) where ascopores are produced.
Pezizomycotina - The sub-phylum is unique compared to the
other sub-phyla in that many of the organisms in this category produce fruiting
bodies. These spore producing organs will be found in such organisms as
perithecia, cleistothecia and chasmothecia among others. Some of the organisms
in this category are saprotroph that obtain their nutrition from a variety of
material such a plant tissues and those that survive through symbiotic
relationships with other organisms.
Also known as conjugation fungi, the phylum Zygomycota is composed of well over 900 species that are categorized as either Zygomycetes (live as parasites of commensals in the gut of arthropods) and Trichomycetes (found in aquatic environments or gut of arthropods).
One of the main traits of these organisms is that they produce zygospores in sexual reproduction. However, some of the organisms under this classification are capable of asexual reproduction and will reproduce through the production of spores known as sporangiophores.
Studies have showed this phylum to bridge
between such lower fungi as slime molds and higher fungi such as Basidiomycota.
Organisms that form the sub-phylum Zygomycota can be found in a wide range of
environments from land to aquatic environments where they obtain their
nutrients as saprophytes (from fruits among others) by living in the guts of
arthropods, through symbiotic relationship with plants and other organisms as
well through parasitism where they infect various plants and animals.
the other traits of phylum Zygomyota include:
- They produce chitin in
their cell wall (a characteristic of all true fungi)
- They tend to grow as
- They form hyphae
- They produce zygospores in their
Also known as Hybrids, Chytridiomycota can be found in a wide range of environments from land to aquatic environment.
Compared to other types of fungi, Chytridiomycota is the only phylum that contains fungi that are capable of moving from one point to another.
These cells, known as zoospores, have developed a posterior flagellum that make it possible for the cell to be motile. Most of the organisms in this phylum are saprophytes and obtain their nutrients from a variety of organic substances in land and aquatic environments. However, some are pathogenic and infect the host by sensing a difference in chemical gradient.
Most of the Chytrids are single
celled organisms with a few being multicellular organisms that may be described
Glomeromycota are fungi with highly branched arbuscules.
They are largely dependent on a symbiotic relationship with plants where many
of them form the arbuscular mycorrhizas with such parts of the plant as roots.
With regards to reproduction, Glomeromycota reproduce through the production of
spores (asexually). Through their association with plants, Glomeromycota obtain
some of the products of photosynthesis from the plant through the arbuscules to
be stored and used by the organism.
Basidiomycota is also one of the largest phylum with well over 30,000 fungi species. They include such organisms as the toadstool and mushrooms and tend to grow as hyphae.
They are characterized by the presence of a basidium, which is a structure that is shaped like a club. Some of the organisms in this category include smuts and rusts.
Other characteristics of this phylum include:
- They exist as either single celled or multicellular organisms
- They can reproduce sexually or asexually
Morphology and Structure of Fungi
There are a wide variety that range
from the smallest unicellular fungi such as yeast to larger multicellular capable of forming hyphal threads or false roots. For this reason, fungi are
also classified according to their morphologies.
The following are
classifications of fungi based on morphology:
Yeast are single celled fungi that can be found
in a variety of environment from soil and plants to animal and aquatic
environments. Unlike bacteria, yeasts are also eukaryotic, which means that
they have different types of organelles that are common in the cells of higher
The Saccharomyces cerevisiae is a good example of yeast that ranges
between 1 and 7 micrometers in size. When viewed under the microscope, these
organisms may be pigmented on their surface.
As with the cells or higher organisms, the S. cerevisiae
contains such organelles as a membrane bound nucleus, a vacuole, mitochondria
and the Golgi apparatus as well as the E.R (endoplasmic reticulum). The cell
wall of these yeast is composed of glucan (a polysaccharide compound) and
As for the genome, research has shown these yeast to carry a
single, linear double stranded DNA that consists of several repeated sequences.
For yeast, the primary mode of reproduction is through budding. Following the
copying of the genetic material, a bud is formed on the surface of the cell
that ultimately breaks off with its genetic material and grows to form a new
Yeast-like fungi are yeast that partly grow like
normal yeast. However, they also attach to each other to form what is known as
a pseudo hyphae (not a true hyphae).
Candida albicans is one of the most common. When viewed under the microscope, these organisms have been
shown to consist of several layers that make up the cell wall.
As with yeast,
the wall of C. albicans contains layers of mannoproteins, lipids and a beta
glucon, a chitin inner layer that strengthen the cell wall. Like yeast, C. albicans also appear
spherical or ovoid in shape and measure between 4 to 8 micrometers.
also reproduce through budding, like yeast, C. albicans may end up creating an elongated
chain of cells as they continue dividing to form the pseudohyphae. However, some studies suggest that some
of the yeast-like fungi tend to form true hyphae in the process.
Yeast-like fungi such as C. albicans are also
described as being polymorphic fungus. This is because they present four types of morphology including the yeast cell, pseudohyphae, hyphae as well as
chlamydospores. As such, they are likely to be seen having varying appearance
when viewed under the microscope depending on such conditions as the
availability of nutrition, pH and temperature among others.
The type of
morphological appearance of these cells has also been associated with the pathogenicity
of the organism. Given that they are not bacteria, some of these organisms
(yeast-like fungi) have characteristics associated with eukaryotic cells in
that some have been shown to contain a nucleus and other essential organelles.
Mold (Mould) are a type of fungi that often
grow well in favorable environments with warmth and moisture. They can be found
growing on various surfaces such as food surfaces from which they obtain their
Compared to yeast, molds are multicellular organisms. As such, they
can be seen with the naked eye without using a microscope. However, when viewed
under the microscope, it is possible to observe numerous filaments (Hyphae)
that are collectively referred to as Mycelium.
While these organisms are
microscopic, it is their numerous hyphae (that form the mycelium) that make it
possible to see mold as it grows on food surface (bread, oranges etc). There
are two main types of mycelium depending on their functions.
Vegetative mycelium - Vegetative mycelium
include the hyphae that penetrates into the substrate and absorbs nutrients for
the continued growth and development of the organisms. These hyphae therefore
act like plant roots.
Aerial mycelium - Aerial mycelium are the hyphae
that are located above the food substance. When viewed closely under the
microscope, aerial mycelium contain a spherical structure at the top of the
hyphae. These are known as the conidia and sere as the reproductive part of the
mold. This part produces spores (asexual reproduction) that can grow in favorable
Dimorphic fungi exist in the form of mold and
yeast. Examples of these fungi include Penicillium marneffei and Mucor
Most of these organisms are capable of switching from between
the two forms in a process commonly referred to as dimorphic switching. As
such, they are viewed as having hyphal threads or as single celled organisms
under the microscope (yeasts).
Uses and Disadvantages of Fungi
As mentioned, there are a wide variety across the world that can be found in different habitats. Depending on the type
of fungi, they can be useful and beneficial or present various disadvantages.
The following are some of the main benefits and disadvantages:
- Molds tend to cause food
damage and can release spores that can cause a range of health problems such as
breathing difficulties. Moreover, molds my release toxins (aflatoxin or
myotoxins among others) that can cause serious health problems to a human
- While mushrooms are
important as food sources, some are poisonous and can cause death when
consumed. A number have been shown to not have an antidote and
therefore cause serious health problems and even death given that there is no
Some of the fungi such as yeast and Candida
albicans tend to be pathogenic and cause serious infections to the host (man).
Importance/Uses of Fungi
Fungi have a variety of uses that make them very
important. These include:
- Mycorrhizal relationship
between some of the fungi and plants benefits various plants in many ways. For
instance, whereas the fungi obtains nutrients from the plant, the fungi may
make various material such as phosphates readily available for the plant.
- Insecticides and medicines
- Some of the fungi act as biological insecticides. For instance, such Fungi as
Beauveria bassiana allow farmers to control such pests as the emerald ash borer
that tend to cause damage to plants. As such, these fungi are important in
agriculture and in homes. On the other hand, such fungi as Penicillum species
are important because they are used to develop vaccines to treat
Some of the other uses include:
- In bakery
- For alcohol
- Help in degradation
of organic material
Continue to read about Unicellular and Multicellular Organisms as well as Heterotrophs.
Return to Microorganisms Main Page
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Carris, L. M., C. R. Little and C. M. Stiles.
2012. Introduction to Fungi. The Plant Health Instructor. DOI:10.
Koji Yokoyama, Haruo Kaji, Kazuko Nishimura and
Makoto Miyaji. The role of microfilaments and microtubules
during pH-regulated morphological transition
in Candida albicans. 1994.
Smith and David Read. Mycorrhizal
Symbiosis. The symbionts
forming arbuscular mycorrhizas. 2008, Pages 13–41.