KINGDOM FUNGI

1. KINGDOM FUNGI

2. Characteristics of Fungi • This kingdom contains heterotrophic eukaryotic organisms that are saprobes, absorbing their food from decaying matter. • Fungi are decomposers. They release digestive enzymes into their immediate environment. These enzymes break down the dead organic matter. Fungi then absorb the digested food through the cell wall. • Slime moulds take up their food by simple endocytosis.

3. The bodies of most fungi consist of threadlike filaments called hyphae. As the hyphae grow, they branch, forming a tangled mass of filaments called a mycelium that is well adapted to absorb nourishment from its food source. • Most hyphae have cell walls strengthened by a substance called chitin, (a long-chain polymer of beta-glucose that forms a hard, semi-transparent material).

4. Reproduction • Most species in this kingdom reproduce asexually and sexually by means of spores. Spores are single reproductive cells that have a haploid number (23) of chromosomes • The 100,000 species of fungi are grouped into divisions based on their pattern of sexual reproduction. (Phyla are called divisions in Kingdom Fungi). • Fungi with spores in a case like structure (sporangium), are placed in division Zygomycota. Fungi with spores in a saclike structure (ascus), are placed in division Ascomycota. Fungi with spores that form in a club like structure (basidium), are placed in division Basidiomycota.

5. Fungi • Heterotrophic • Absorb nutrients • Most are saprobic • Can grow in a variety of habitats. • Some pathogens • Smuts & rusts on plants • Mycoses in animals

6. Fungal Morphology • Single-celled fungi • Yeasts • Reproduction • Can reproduce asexually or sexually • Budding • Saccharomyces cervisiae • Binary fission • Schizosaccharomyces pombe Budding Yeast

7. Fungal Morphology • Filamentous fungi • Hypha: single filament • Mycelium: collection of hyphae • Examples: • Molds • Mushrooms • Puffballs • Dimorphic fungi Nester et al (2007) Microbiology: A Human Perspective, 5th ed., McGraw-Hill, New York, NY, p. 306

8. Case like Fungi (Division Zygomycota) • Terrestrial saprobes. One common mould is bread mould, or Rhizopus. • Mycelium grows and produces several types of hyphae. These hyphae (rhizoids) extend into the food source like roots of a plant. They absorb water and sugar from the bread supporting further growth. • Favourable conditions - sporangia grow at the tips of the hyphae. Each containing thousands of spores - transmitted to other food sources via air currents. (asexual reproduction). • Less favourable conditions -reproduces sexually through conjugation forming a zygospore which remains dormant until the growing conditions improve.

9. Rhizopus aka Bread Mould

10. Sac like Fungi (Division Ascomycota) • Characterized by a sac structure used in reproduction. Include the mildews, some moulds, and some yeasts. • Sac fungi produce two kinds of spores. Spores produced as a result of sexual reproduction are called ascospores. They are produced in an ascus or sac. Spores produced asexually are called conidia. • Examples: Powdery mildews are parasitic ascocarps that infect cereal grains, lilacs, roses and other plants. A truffle is an ascomycete that forms fruiting bodies underground. They are considered a delicacy and sell for hundreds of dollars.

11. Yeasts are unicellular. Some are grouped with the ascomycetes because they form an ascus in one stage of their life cycle. • Yeasts can tolerate conditions lacking oxygen and carry out anaerobic respiration, or fermentation. In this process, sugar molecules are broken down by enzymes in the yeast cells, releasing energy, carbon dioxide and alcohol. • Bakers yeast is added to dough and the carbon dioxide released causes the dough to rise. Wine makers use strains of yeasts that generate high volumes of alcohol. • Some yeasts cause infections in the skin, lungs, and kidneys. Many are parasitic and cause disease. • Morels are famous because they are so good to eat! - grow in rich soils

12. Sac like Fungi Division Ascomycota

13. Club like Fungi (Division Basidiomycota) • This division includes mushrooms, rusts, smuts, puffballs, bracket fungi and some yeasts. • Many are saprobes and others are parasites. • Under damp conditions in soil or in rotting wood, the mycelial mass of hyphae form knobs that absorb water and grow quite large. These knobs become spore bearing structures called fruiting bodies. • Spores are produced on microscopic, club-like structures called basidia

15. Parasitic rusts and smuts make up another important group of fungi. These cause damage to grain crops such as corn, oats, wheat, rye and barley. • Bracket fungi can exist as saprobes on the wood of dead trees, or as parasites on the wood of living trees. • Puffballs are round or pear-shaped fungi. Often white and resembling mushrooms they release their spores only when the fruiting body dries up and splits open.

17. Imperfect Fungi (Deuteromycota) • Have no known sexual phases and so cannot be classified into divisions. • Many cause diseases in plants and animals, including humans. • E.g. In 1928 Sir Alexander Fleming observed a green mould Penicillium growing on a petri dish containing Staphylococcus bacteria. He later isolated a chemical substance produced by the fungus (Penicillin). This was the first antibiotic to come into medical use. This prevents the formation of cells walls or cell membranes in reproducing bacteria. • The common mould Trichophyton rubrum causes a contagious fungal infection called athlete’s foot.

18. Fungal Associations • Certain fungi associate with other organisms for the mutual benefit of both partners. • Lichens are symbiotic associations of a fungus with either an alga or a cyanobacterium. The alga provides nourishment to the fungus through photosynthesis. The fungus provides the alga with water, essential minerals, and protection from dryness in barren and rocky habitats. • Other fungi associate with the roots of plants. These associations are known as mycorrhizae. The fungus mycelium forms a thick web over the surface of a plant’s roots. The fungal mycelium absorbs water and minerals from the soil, which it passes to the root. The plant provides the fungus with amino acids and sugars. • Still other fungi associate with leaf-cutting ants. The ants provide food for the fungi until it grows large enough to serve as food for the ants.

19. Lichens

20. Lichen Ecology • Lichens can grow in very inhospitable environments. (rocks, gravestones, sides and branches of trees etc.) • Lichens are very sensitive to air pollution, especially sulfur and nitrogen, and so they are natural indicators of air quality. • Grow extremely slowly, usually 1-2 mm per year. • Lichen uses: break down rocks into soil, food source for caribou/ deer in the tundra, natural dyes, tweed

21. Fungi Pros • Yeasts- baking and brewing • Antibiotics and drugs (penicillin, cephalosporin) • Many organic acids are commercially produced with fungi. Eg. Citric acid in Coke is produced by an Aspergillus. • Steroids and hormones eg. The pill • Certain stinky cheeses eg. Blue cheeses, roquefort and camembert.

22. Fungi Cons • Can cause human disease, either directly or through their toxins. • Can cause diseases in plants and animals (crops, etc.) • Cause rot and contamination of foods. • Can destroy almost every kind of manufactured good, with the exception of plastics and some pesticides.

28. Fungi Review Questions 1. In which division in the kingdom Fungi are mushrooms found? a) Zygomycota b) Ascomycota c) Basidiomycota d) Imperfect Fungi 2. What are some similarities and differences between fungi and plants? 3. Describe the roles of fungi as decomposers and as parasites. Give examples. 4. What are mycelia and hyphae? 5. What carbohydrate is in the cell wall of fungus? 6. a) What are the parts of a lichen? b) What does each contribute to the other? c) Why are lichens important? 7. Given your knowledge of fungi, what growth conditions might favor the fungus that causes athlete’s foot? 8. a) With which kind of organism are mycorrhizae associated? b) Why are they not considered parasites? c) What role is played by each member of the relationship? 9. The reproductive cells of fungi are called _____. 10. What is a saprobe? 11. Explain the difference between a saprobe and a parasite. 12. What characteristic of yeast makes it an unusual fungus? 13. Certain types of mushrooms grow only at the base of a particular species of tree. Explain. 14. What kind of fungus is used to make penicillin? 15 What advantage would a fungus that produces an antibiotic have over one that does not? 16. Most mushroom mycelia grow in the soil. Why do mushroom fruiting bodies grow above ground? 17. What are some of the other uses humans have found for fungi? 18. A spore may develop hundreds of kilometers away from its origin. Explain how this is so. 19. a) Fungi use what type of nutrition? b) They obtain food how? 20. Which of the following conditions are likely to be the most suitable for the growth of fungi a) warm and dry (b) light and dry (c) dark, cool and humid (d) light, warm and humid