What types of fungi are there

Since they do not possess the sexual structures that are used to classify other fungi, they are less well described in comparison to other divisions. Most members live on land, with a few aquatic exceptions. They form visible mycelia with a fuzzy appearance and are commonly known as mold.

Molecular analysis shows that the closest group to the deuteromycetes is the ascomycetes. In fact, some species, such as Aspergillus, which were once classified as imperfect fungi, are now classified as ascomycetes. Reproduction of Deuteromycota is strictly asexual and occurs mostly by production of asexual conidiospores Figure 8.

Some hyphae may recombine and form heterokaryotic hyphae. Genetic recombination is known to take place between the different nuclei. Figure 8. Aspergillus niger is an imperfect fungus commonly found as a food contaminant. The spherical structure in this light micrograph is a conidiophore.

Imperfect fungi have a large impact on everyday human life. The food industry relies on them for ripening some cheeses. The blue veins in Roquefort cheese and the white crust on Camembert are the result of fungal growth. The antibiotic penicillin was originally discovered on an overgrown Petri plate, on which a colony of Penicillium fungi killed the bacterial growth surrounding it.

Many imperfect fungi cause serious diseases, either directly as parasites which infect both plants and humans , or as producers of potent toxic compounds, as seen in the aflatoxins released by fungi of the genus Aspergillus. The Glomeromycota is a newly established phylum which comprises about species that all live in close association with the roots of trees.

Fossil records indicate that trees and their root symbionts share a long evolutionary history. It appears that all members of this family form arbuscular mycorrhizae : the hyphae interact with the root cells forming a mutually beneficial association where the plants supply the carbon source and energy in the form of carbohydrates to the fungus, and the fungus supplies essential minerals from the soil to the plant.

The glomeromycetes do not reproduce sexually and do not survive without the presence of plant roots. Although they have coenocytic hyphae like the zygomycetes, they do not form zygospores.

DNA analysis shows that all glomeromycetes probably descended from a common ancestor, making them a monophyletic lineage. Chytridiomycota chytrids are considered the most primitive group of fungi. They are mostly aquatic, and their gametes are the only fungal cells known to have flagella. They reproduce both sexually and asexually; the asexual spores are called zoospores. Zygomycota conjugated fungi produce non-septated hyphae with many nuclei.

Their hyphae fuse during sexual reproduction to produce a zygospore in a zygosporangium. Ascomycota sac fungi form spores in sacs called asci during sexual reproduction.

Asexual reproduction is their most common form of reproduction. Basidiomycota club fungi produce showy fruiting bodies that contain basidia in the form of clubs. Spores are stored in the basidia. Most familiar mushrooms belong to this division.

Deuteromycota imperfect fungi belong to a polyphyletic group that does not reproduce through sexual reproduction. Asexual reproduction is by means of spores produced in sporangia borne on the hyphae. Zygomycota get their name from the production of thick-walled sexual structures called zygosporangia, which can remain dormant for long periods.

The Ascomycota comprise about 30, described species, among them most of the blue-green, red, and brown molds that cause food spoilage, including the salmon-colored bread mold. Ascomycetes are the causes of a number of serious plant diseases, like Dutch elm disease, but the group also includes edible morels and truffles. This group is also comprised of the yeasts used in the production of beer, wine and bread.

With the exception of unicellular yeasts, the Ascomycetes are filamentous during development and their hyphae are septate divided into cells. Reproduction is usually by the formation of specialized spores, called conidia, borne at the tips of hyphae in specialized structures conidiophores.

Aquatic fungi in this group are predominantly found on submerged wood, but others are free floating or found on sediments and algae. The fungal group Basidiomycota, also known as the club fungi, includes some of the most familiar fungi. Within this group of 16, species are the mushrooms, toadstools, shelf fungi, and puffballs.

Basidiomycetes play a key role in the environment as decomposers of plant litter. They are distinguished from other fungi by their production of basidiospores, which are borne outside a club-shaped, spore-producing structure called a basidium.

This group is poorly represented in the aquatic environment. There are very few species of freshwater species known and the majority of marine species are free- floating with a couple of lignicolous found on wood species. The Deuteromycota, or conidial fungi, are a group of about 17, distinct species in which the sexual reproductive features are either not known or are not used to classify them.

Their lack of sexual stages was the basis for them being called fungi imperfecti in the past. The term fungi imperfecti was misleading because these fungi are abundant and flourishing.

It could well be that at the genetic level the two are very different from each other. Now, new species descriptions for fungi typically require both DNA sequences ideally from several different sections of their DNA and their morphological descriptions.

How these differences are classified can have a huge influence on how many types of fungi we think exist. Interestingly, one of the most commonly used databases for that is Genbank , which was developed at Los Alamos in the early s.

It is used for many types of organisms, not just fungi. The question then of how you define a species becomes quite complex. What piece of DNA do you use? Then, the smaller molecules produced by this external digestion are absorbed through the large surface area of the mycelium. As with animal cells, the polysaccharide of storage is glycogen rather than the starch found in plants. Fungi are mostly saprobes saprophyte is an equivalent term : organisms that derive nutrients from decaying organic matter.

They obtain their nutrients from dead or decomposing organic matter, mainly plant material. Fungal exoenzymes are able to break down insoluble polysaccharides, such as the cellulose and lignin of dead wood, into readily-absorbable glucose molecules. The carbon, nitrogen, and other elements are thus released into the environment.

Because of their varied metabolic pathways, fungi fulfill an important ecological role and are being investigated as potential tools in bioremediation. Some fungi are parasitic, infecting either plants or animals. Fungi can reproduce asexually by fragmentation, budding, or producing spores, or sexually with homothallic or heterothallic mycelia.

Perfect fungi reproduce both sexually and asexually, while imperfect fungi reproduce only asexually by mitosis. In both sexual and asexual reproduction, fungi produce spores that disperse from the parent organism by either floating on the wind or hitching a ride on an animal. Fungal spores are smaller and lighter than plant seeds. The giant puffball mushroom bursts open and releases trillions of spores. The huge number of spores released increases the likelihood of landing in an environment that will support growth.

The release of fungal spores : The a giant puff ball mushroom releases b a cloud of spores when it reaches maturity. Fungi reproduce asexually by fragmentation, budding, or producing spores. Fragments of hyphae can grow new colonies. Mycelial fragmentation occurs when a fungal mycelium separates into pieces with each component growing into a separate mycelium. Somatic cells in yeast form buds. During budding a type of cytokinesis , a bulge forms on the side of the cell, the nucleus divides mitotically, and the bud ultimately detaches itself from the mother cell.

The most common mode of asexual reproduction is through the formation of asexual spores, which are produced by one parent only through mitosis and are genetically identical to that parent.

Spores allow fungi to expand their distribution and colonize new environments. They may be released from the parent thallus, either outside or within a special reproductive sac called a sporangium. Types of fungal reproduction : Fungi may utilize both asexual and sexual stages of reproduction; sexual reproduction often occurs in response to adverse environmental conditions.

There are many types of asexual spores. Conidiospores are unicellular or multicellular spores that are released directly from the tip or side of the hypha. Other asexual spores originate in the fragmentation of a hypha to form single cells that are released as spores; some of these have a thick wall surrounding the fragment. Yet others bud off the vegetative parent cell. Sporangiospores are produced in a sporangium. Release of spores from a sporangium : This bright field light micrograph shows the release of spores from a sporangium at the end of a hypha called a sporangiophore.

The organism depicted is a Mucor sp. Sexual reproduction introduces genetic variation into a population of fungi. In fungi, sexual reproduction often occurs in response to adverse environmental conditions. Two mating types are produced. When both mating types are present in the same mycelium, it is called homothallic, or self-fertile.