Zygomycota
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Zygomycota is a taxonomic phylum of fungi characterized by structures that produce resistant spherical spores during sexual reproduction (zygosporangia). Approximately 1060 species of zygomycetes are known. Many are molds, which serve as important decomposers. They are mostly terrestrial in habitat, living in soil or on decaying plant or animal material. Some are parasites of plants, insects, and small animals, while others form symbiotic relationships with plants.
Anatomy
The phylum Zygomycota contains the classes Zygomycetes and Trichomycetes. Class Trichomycetes are parasites that live inside the guts of arthropods. They are usually found in the guts of herbivorous and/or detrivorous organisms. They are sometimes found in predaceous organisms, but that is very rare. One species of Class Trichomycetes is capable of inhabiting more than one host species. Class Zygomycetes contains the off-branch of Zygosporangia, which are mainly known for their sexual reproduction by physical blending. [1] One of the orders of Zygomycota that is closely related to Zygomycetes is Mucorales. One of its members is Pilobolus crystallinus, which is the first fruit fungi to have started breeding in dung. They have unbranched sporangiophores which are about two to four centimeters high, which "fire" their spores out toward any light shining on them. [2] [3]
Zygomycota is a rather dark color, usually green or black, but can also be white, which is most common. Zygomycota is usually thought of as just the mold that affects bread after a lengthy period of time, but it is also capable of forming a symbiotic relationship with plants and/or animals. Two common names that are used to describe Zygomycota are pin molds and sugar molds. The sugar molds are the type that affect fruit rich with sugars, and pin molds refers to the appearance of other species. [4]
One of the other anatomical mysteries of certain types of mold is their ability to change form. Some kinds of mold can change their species, family, and sometimes even their phylum. There are also kinds of mold that will change themselves into yeast and back again, which would explain why bread might mold. Molds can also be a danger to living organisms after they, meaning animals, have died. Certain toxins released from dead mold can threaten the health of just about any life, including humans. [5]
Reproduction
In the process of sexual reproduction, a positive mating type and a negative mating type, also known as Isogametangia and Anisogametangia, bond together to form Gametangia with haploid nuclei in a process called Plasmogamy. Between two appendages, officially known as progametangia, of the opposite mating types, a structure is formed called Zygosporangia, which is released from the mating types in a process called Karyogamy. The Zygosporangia is released with diploid nuclei, and through a process called meiosis grows an appendage. On the end of the appendage is a sporangium, which releases spores that form into Mycelia through a process called dispersal and germination. Some of the mycelia change back into the two different mating types that were in the first stage. Other spores will become mycelia as well, but will become part of another process called asexual reproduction. The spores that are released from the sporangium used in asexual reproduction are called sporangiospores. Three sporangia are produced, and the nuclei form septa by moving the ends of the progametangia together. The three sporangia produce more spores that will return to the beginning of asexual reproduction, and be used to create more septa.[6]
When it comes to other different kinds of mold, there are many different ways of reproducing and distributing their spores. A fungus that grow on the dung of animals called Pilobolus has a very unique way of distributing its spores. It bends certain appendages called sporangiophores towards the light. At the bottom of the bulbous head of the sporangiophores, there is a light sensitive retina that causes the whole structure to bend towards that light source. This causes great pressure, more than one hundred pounds per square inch, and project the spores in the direction of the light source when the head explodes in hopes of them landing on a plant of some sort. [7] That way, the animal that comes along and eats the plant will ingest the spores, and eventually produce them in its dung. [8]
One of the off-branches of Class Zygoycetes, one of the classes under Zygomycota, is known specifically for its sexual reproduction. It is called Zygosporangia. In Greek, the word "Zygos" means either yoke or joining. Zygosporangia blends gametangia to form a zygosporangium, which is used in the heterokaryotic stage of plasmogamy. [9] From there, it continues on through the process of normal Zygomycotic sexual reproduction. [10] Zygosporangia are also involved with asexual reproduction. They have what are called "anamorphic phases," which are usually found on things such as bread and fruit when they are moldy. There's also a species called coprophilous fungi that can be found in horse dung exhibiting asexual reproduction. [11]
Ecology
Zygomycota is one of the most diverse groups of fungi. They are terrestrial, and they live close to plants in order to keep their constant food supply. Zygomycota decomposes things such as soil, dung, and almost any kind of plant matter, making its role in the carbon cycle enormous. They also form many different kinds of relationships, such as mutualistic symbiotic relationships with many different kinds of plants. They also form commensalistic relationships with arthropods, in exchange for unused nutrients. Zygomycota can also be found in aquatic environments. [12]
Molds can be found in many different places. Not only do they begin to grow on fruit and bread after an elongated period of time, they also grow inside the very walls of homes all over the world. Molds tend to grow in places where there are high quantities of moisture. They will eat out the insides of wall, decks, and even chimneys. They can also have an effect on the person or persons inhabiting the house. Some people might have allergic reactions, while others might feel an effect on their memory, balance, and the abilities to concentrate and sleep. [13]
Zygomycota can also make an economical dent in society as well. All the perishable items that are sold in grocery stores must be protected from the powers of mold. If the proper precautions are not taken, the fruit will be spoiled, and that loss of merchandise will cause a change in the economy, though probably not that large. [14]
Mold is also a common cause for certain diseases. They can cause serious health challenges for those who are in a poor state of health. If someone with diabetes gets infected by some kind of mold, it an extreme health hazard, and quite possibly could be lethal. The most likely place that the mold would cause an infection would be the upper respiratory track. If someone with diabetes is having trouble breathing, it is probably due to an infection by mold. [15]
The Effect of Mold on Living Organisms
Mold is mainly known for the negative impact that it has on food and homes, but it also has practical uses. There are certain Asian foods that have mold in their fermentations. They can also be used as a method of pest control. There are also certain species of Zygomycota that are capable of forming relationships with animals.
While molds do have some practical uses, they can also be very dangerous. They have been known to cause serious infections for diabetic and immunocompromised individuals. Mold can also cause these kinds of infections where major burns or other traumatic injuries might be located. One potentially lethal disease caused by Zygomycota is Zygomycosis. It is rare fungal disease that affects humans. There are three clinical forms of the disease: cellulitis, disseminated, and gastrointestinal. When the disease has entered the gastrointestinal stage, its symptoms are basically the same as that of another disease which is called Necrotizing Enterocolitis, also known as NEC. It is because of this that the diagnosis of the disease can be mistaken for one or the other. [16]
There are also other mold fungi that can be dangerous to insects. In the Order of Entomophthorales, one of the orders of Zygomycota, there is a fungus that threatens houseflies. Entomophthora muscae literally eats the fly from the inside out. The infected fly lays itself out in an exposed area, and lets the mold kill it. The mold breaks out of the insect's exoskeleton and produces small masses of tightly-packed sporangiophores. When the sporangiophores reach maturity, they produce a sticky, unicellular organism that is called a mitosporangium. If there are any flies nearby when the barrage is released, they will also become infected. There is also another type that is part of the Class Trichomycetes that inhabits the larvae of mosquitoes. It matures faster than the larvae and, as a result, end up killing it. [17]
Gallery
Moldy Bread
(Rhizopus stolonifer)
Order: Mucorales
References
- Zygomycota Curtis Clark. Microbewiki. 2002.
- Kingdom Eumycota Anonymous. Mycologue publications. August 22, 2006.
- Zygomycota Anonymous. Wikipedia, part of the wikimedia foundation. Febuary 25, 2009.
- Mold: The Whole Picture Pt. 1 Ellen McCrady. The Abbey Newsletter. 1999.
- Molds: General Information U.S. Center for Disease Control
