Chapter 26 Kingdom Eumycota (Fungi).
Total worldwide of 100,000 species, fungi are
mainly saprophytes (decomposers that absorb organic molecules from dead organisms).
Secrete enzymes that digest organic materials outside the body, then absorb the small molecules that are produced.
Cell wall is made of chitin. Fungi consist of thread-like hyphae that form a connected network : a mycelium
Sexual reproduction : the cytoplasm of two cells join in plasmogamy, later the two nuclei join in karyogamy.
Fungi reproduce using spores.
Fungi can infect people with weak immune systems. Infections. On the other hand they are a good source of antibiotics: New. Other medical products from fungi include cyclosporin which is given to transplant recipients to lower their immune system. Also statin drugs that reduce the risk of heart attack are obtained from fungi. Both of these drugs have sales of over $1 billion a year.
Phylum Zygomycota
1000 species.
Reproduce by forming a single zygospore that can resist harsh environments.
Hyphae are coenocytic (nuclei are not separated from each other by cell membrane or cell wall).
Mainly saprophytes, but some form mycorrhizae in plant roots, which helps the plant obtain nutrients.
Examples : Rhizopus bread mold.
Rhizopus oligosporous is used in making tofu and tempeh.
Arthrobotrys kills nematode worms in the soil, and so improves crop yields. Video
Pilobolus artillery fungus : shoots spores away from dung. Video
Phylum Ascomycota
60,000 species. they form 8 ascospores in a long cell called an ascus.
Many are mutualistic with algae, forming lichens. Lichens grow on rocks or trees (they are photosynthetic), and are important sources of food in cold climates (reindeer eat mainly lichen). They are also very sensitive to air pollution, so several cities regularly survey lichens to sample the air quality. Lichens can also survive the harsh conditions of space.
Examples : Claviceps purpurea causes ergot disease in crops, and St. Anthonys fire in humans.
Penicillium used in making antibiotics, blue cheese and salami.
Saccharomyces is yeast. Used in baking and brewing (Note: this is different from the "yeast" that causes infections).
Tuber melanosporum truffles are edible and very expensive. They are collected using pigs, or dogs, to locate the fungus which is often buried deep in the leaf litter. Truffles and crime!
Phylum Basidiomycota
30,000 species, mainly saprophytes. Form 4 basidiospores in a club shaped basidium.
Examples : Agaricus the common mushroom.
Growing mushrooms
Phallus or stinkhorn. The spores are dispersed by flies attracted to the smell of rotting meat.
Puccinia graminis causes wheat rust. It overwinters in barberry (genus Berberis) where it produces spores in a cup-shaped aecium. Aecium. In the spring and summer spores infect wheat, and spread from uredia that burst through the leaf. Uredia.
Armillaria is the largest living fungus, with a single individual able to cover several acres (underground), and live for over 1,000 years! Giant fungus
Amanita fly agaric is hallucinogenic and was used by Vikings!
Fly agaric
Smuts, such as Ustilago infect crops like corn.
Smut
Phylum Deuteromycota (Imperfect Fungi)
Artificial group : no sexual reproduction has been observed.
Often a temporary category, until a fungus is studied in detail.
Examples : dermatophytes cause athlete's foot.
Aspergillus : used for making soy sauce, and saki.
It is also a source of citric acid for soft drinks, which has a huge commercial value (look at the ingredients list on your soft drink!).
Peanuts infected with Aspergillus contain aflatoxins that cause liver cancer, particularly in Africa and Asia.
Last edited September 2009, David Byres, dbyres@fscj.edu