Phylum Chytridiomycota & Zygomycota

Editor's Notes

1. Chytridiomycota, a phylum of kingdom Fungi distinguished by having zoospores (motile cells) with a single, posterior, whiplash flagellum They are informally know as “Chytrids” This term referred just to organisms in the class Chytridiomycetes Interesting there are other classes; Class Monoblepharidiomycetes Class Hyaloraphidiomycetes Over 750 Chytrid species Distributed among ten (10) orders The name is derived from the Greek chytridium, meaning "little pot“ Little pot describing the structure containing unreleased zoospores Chytrids are one of the early diverging fungal lineages, and their membership in kingdom Fungi is demonstrated with; chitin cell walls Posterior whiplash flagellum Absorptive nutrition Glycogen as energy storage compound Saprophytic/parasitic
2. What is their Modus operandi? Species are microscopic in size, and most are found in freshwater or wet soils Obviously these sperm-like cells require water and it is thus not surprising that chytrids live in perminantly or temporarily aquatic habitats. Chytrids mainly infect algae and other eukaryotic and prokaryotic microbes Affect plants and animals Few species in the order Chytridiales cause plant disease Synchytrim endobioticum Synchytrium endobioticum is a fungus that causes potato wart disease, or black scab. This disease affects the shapes of the tubers of potatoes. The fungus cause a de-shapes in potatoes, thus, become tasteless loosing its flavor and therefore unfit for human consumption. You tubers get deformed due to infection and have to be thrown away one species, Batrachochytrium dendrobatidis, has been shown to cause disease in frogs and amphibians – Chytridiomycosis Amphibians Frog, salamander, toads, caecilian,
3. What makes Chytrids unique among fungi? The Chytridiomycota, often called chytrids, are unique among all fungi in having motile stages in their life cycles; no other fungi have this trait. These motile stages take the form of zoospores, single cells with a single posterior (at the rear) flagellum
4. Extracellular enzymes or Exoenzymes are synthesized inside the cell and then secreted outside the cell, where their function is to break down complex macromolecules into smaller units to be taken up by the cell for growth and assimilation These enzymes degrade complex organic matter such as cellulose and hemicellulose into simple sugars that enzyme-producing organisms use as a source of carbon, energy, and nutrients. Grouped as hydrolases, lyases, oxidoreductases and transferases These enzymes target macromolecules such as carbohydrate (cellulases), lignin (oxidases), organic phosphate (phosphatases), amino sugar polymers (chitenases) and proteins (proteases)
5. Some do live in the soil Sirenin comes from the Sirens, mythological Greek figures who called to sailors in an attempt to lure their ships onto the rocks so they could capture the ship’s goods.
6. Alternation of generations is rare in fungi, but it appears in all plant phyla and in many algae
7. What features of Chytrids makes them germane to the lives of other organisms, similar organisms or the environment in which they dwell. Decomposer aid in the reduction of waster/organic matter/ or rubbish in the environment and are very important in any ecosystem They decompose/ breakdown substance with different organism molecules. Eg: chitin, keratin, cellulose among others Coelomomyces is a genus of fungi in the family Coelomomycetaceae. Species in the genus can be used as agents for the biological control of mosquitoes These species affect the population of mosquitoes species and have been studied extensively Entomopathogenic fungus fungus that can act as a parasite of insects and kills or seriously disables them. For the Record: Of the 56.9 million deaths worldwide in 2016, more than half (54%) were due to the top 10 causes. Ischaemic heart disease and stroke are the world’s biggest killers, accounting for a combined 15.2 million deaths in 2016. These diseases have remained the leading causes of death globally in the last 15 years. The leading causes of death in the world - can they be cured? Ischaemic heart disease (coronary artery disease) Stroke. ... Lower respiratory infections. ... Chronic obstructive pulmonary disease (COPD) ... Lung cancer, trachea and bronchus. ... Diabetes. ... Alzheimer's disease. ... Diarrhoeal diseases. . Afirca 738 million people living in the African Region of the World Health Organization. The World Health Organization’s most recent data on global deaths has good news for the African continent, including fewer people dying of HIV/AIDS and malaria. The new death statistics researched by African fact-checking organization, Africa Check, indicated that lifestyle diseases have taken over as the leading causes of death on the continent. Lower respiratory tract infections The most common diseases under this category is bronchitis or pneumonia which is responsible for 16% of global deaths of children younger than five. 2. HIV/AIDS 3. Diarrhoeal 4. Stroke 5. Ischaemic heart disease [Heart attack] – narrowing of the arteries of the heart due to the buildup of plaques causing less oxygen to reach portions of the heart. When fully blocked, damage is caused to the heart and death occurs Malaria [Africa] Malaria is a life-threatening disease caused by parasites that are transmitted to people through the bites of infected female Anopheles mosquitoes. It is preventable and curable. There are 5 parasite species that cause malaria in humans, and 2 of these species – P. falciparum and P. vivax – pose the greatest threat. In 2017, P. falciparum accounted for 99.7% of estimated malaria cases in the WHO African Region In 2017, there were an estimated 219 million cases of malaria in 87 countries. The estimated number of malaria deaths stood at 435 000 in 2017.
8. Batrachochytrium dendrobatidis – Chytridiomycosis
9. Batrachochytrium salamandrivorans What is chytridiomycosis? How does Bd kill amphibians? Chytridiomycosis (“Mycosis” = disease caused by a fungus) is the disease that occurs when an amphibian is infected with large numbers of the Bd fungus. Infection with Bd occurs inside the cells of the outer skin layers that contain large amounts of a protein called “keratin”. Keratin is the material that makes the outside of the skin tough and resistant to injury and is also what hair, feathers and claws are made of. With chytridiomycosis, the skin becomes very thick due to a microscopic change in the skin that pathologists call “hyperplasia and hyperkeratosis”. These changes in the skin are deadly to amphibians because— unlike most other animals— amphibians “drink” water and absorb important salts (electrolytes) like sodium and potassium through the skin and not through the mouth. Abnormal electrolyte levels as the result of Bd-damaged skin cause the heart to stop beating and the death of the animal (Voyles et al., 2009). Other amphibians like the lungless salamanders, use the skin to breathe and skin changes due to chytridiomycosis could interfere with this function causing suffocation. Batrachochytrium dendrobatidis attacks amphibians by infecting their outer skin layers. Frog uses it’s outer skin to hydrate, control their body temperatures, regulate minerals and nutrients, and sometimes even breathe [cutaneous respiration] Cutaneous respiration is a form of respiration in which gas exchange occurs across the skin or outer integument of an organism rather than gills or lungs. Eg: Earthworms and Amphibians. Frog breaths through its skin. It has a permeable skin, which needs to remain moist and have tiny blood vessels or capillaries that lie close to their skin surface. These tiny vessels transports oxygen to their various tissues and carry CO2 to the outer skin layer The infection makes the skin thicker and less permeable, resulting in electrolyte imbalances, loss of muscle control, and heart failure. Frogs may also become lethargic and have redden or sloughed off skin Several treatments have shown promise but there is currently no cure. One key may lie in figuring out why some species are more susceptible than others - some species are resistant whiles other experience 85-100% fatality.
10. Zygomycota are defined and distinguished from all other fungi by sexual reproduction via zygospores following gametangial fusion The phylum comprises at least seven phylogenetically diverse orders [7 orders] Zygomycota are arguably the most ecologically diverse group of fungi, functioning as saprophytes on substrates such as fruit, soil, and dung (Mucorales), as harmless inhabitants of arthropod guts (Harpellales), as plant mutualists forming ectomycorrhizae (Endogonales), and as pathogens of animals, plants, amoebae, and especially other fungi
11. 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, whi le others form symbiotic relationships with plants Coprophilous funig [Dung-loving fugi] Are a type of saprobic fungi that grow on animal dung The fungi then flourish in the feces, before releasing their spores to the surrounding area.
12. Unlike the so-called 'higher fungi' comprising the Ascomycota and Basidiomycota which produce regularly septate mycelia, most Zygomycota form hyphae which are generally coenocytic because they lack cross walls or septa.
13. There are three main categories of life cycles in eukaryotic organisms: diploid-dominant, haploid-dominant, and alternation of generations. 1. Diploid-Dominant Life Cycle. In this type of life cycle the multicellular diploid stage is the most obvious life stage The haploid stage is the production of haploid cells which are gametes It occurs with most animals, including humans 2. Haploid-Dominant Life Cycle. In this life cycle the multicellular haploid stage is the most obvious life stage Most fungi and algae employ a life cycle in which the “body” of the organisms, the ecologically important part of the life cycle, is haploid This is associated with positive and negative mating types The haploid multicellular stage produces specialized haploid cells by mitosis that fuse to form a diploid zygote. The zygote undergoes meiosis to produce haploid spores. Each spore gives rise to a multicellular haploid organism by mitosis. 3. Alternation of Generations. Employ by some algae and all plants Blend of the haploid-dominant and diploid-dominant extremes Species here have both haploid and diploid multicellular organisms as part of their life cycle Haploid multicellular plants are called gametophytes [n] Diploid multicellular plants are called sporophyte [2n] Stable Environment [Asexual reproduction] Moist Presence of light Available food / organic matter Absent of mating type Unstable Environment [Sexual reproduction] Dry environment Dark, absence of light Absent of food/organic matter Present of opposite mating types What makes an environment stable? Sporangia are what you see when you spot the mold growing on a slice of bread. By the time sporangia form, the lightly pigmented mycelium has grown for at least several days and has thoroughly penetrates the bread
14. Asexual reproduction [Stable env.] In a stable environment asexual reproduction predominates Mycelium extends specialize hyphae, called stolon, across the surface of the food Wherever the stolon touches the surface, rhizods grow into the food Rhizoids anchor upright hyphae called sporangiophhores, each forming sporangium at its tip Sporangium is what you see when you spot the mold growing on the bread This shows that the mycelium has thoroughly penetrated the bread When the sporangium breaks apart, spores are released and when they fall in a suitable environment they will germinate and begin the asexual life cycle again Sexual Life cycle [Unstable Env.] Variety of conditions such as; a dry environment, shortage of food, even the mere presence of opposite mating types, can trigger the sexual life cycle Mycelium of + and – mating types releases chemicals that cause hyphae of opposite mating types to grow towards each other On contact, each hyphae forms a gametangium consisting of a single cell with multiple nuclei Fusion of the gametangia (plasmogamy) produces a zygosporangium which contain nuclei of both mating types Zygosporangium develops into a thick, resistant wall containing single zygospores Kaygogamy [Nuclei fusion] occurs inside the zygospores, the diploid nuclei upon fusion undergo MEIOSIS, forming haploid nuclei Zygospore upon germination produces a sporangiophore with a sporangium at its tip The haploid nuclei then undergo MITOSIS and move into the sporangium where they become spores Rapture of the sporangium releases the spores, which may germinates and produce new mycelia
15. Molds are typically identified based on their spores and the structure of the parts of the mold that produces the spores Since the structure of the spore-forming component of the mold can really only be seen using a microscope, the focus here will be on the spores themselves for identifying the type of bread mold The easiest way to identify bread mold at home is based on the general appearance of the mold
16. This mold looks fuzzy on bread, and when it first grows, it tends to appear light in color (either blue, green, or white) Overtime, as spores are produced at the ends of aerial hyphae, the mold spot becomes black in color R. Stolonifer grows in circular patches, and will quickly expand over the surface of the bread
17. Penicillium sp. are the other most common types of mold found on breads. It appears as fuzzy patches that are lightly colored, tending to be white, gray, or blue Pencillium sp. can grow in colder temperatures, and so can be found on bread stored in the refrigerator. The Pencillium molds, if left to grow, can begin to produce mycotoxins which can ultimately prove to be fatal if consumed regularly or in large quantities. Mycotoxins [Mycotoxicosis] Are toxic compounds that are naturally produced by certain types of moulds (fungi) Moulds that can produce mycotoxins grow on numerous foodstuffs such as cereals, dried fruits, nuts and spices There are five mycotoxins, or groups of mycotoxins, that occur quite often in food: deoxynivalenol/nivalenol; zearalenone; ochratoxin; fumonisins; and aflatoxins. Effect: Affect the nervous system of horses May cause cancer in rodents Trichothecene – can be absorbe easily in food Affect the gastrointestinal tract, skin, kidney, liver, and immune and hematopoietic progenitor cellular system The adverse effects on human heath can be both acute and chronic. It can provoke problems such as liver cancer, reduction of immunity, alterations in protein metabolism, gangrene, convulsions, respiratory problems, among others 3. Cladosporium sp. 4. Asperqillus sp.
18. Help to decay organic matter thus playing a major role in the carbon cycle Conversely, some species have a negative economic impact on human affairs by causing storage rots of fruits (particularly strawberries by Rhizopus stolonifer ), as agents of plant disease (e.g., Choanephora cucurbitarum flower rot of curcurbits), while other species can cause life-threatening opportunistic infections of diabetic, immuno-suppressed, and immuno-compromised patients