THE FUNGUS AMONGUS

FUNGI

• Eukaryotes – uni or multicellular• Most are composed of

filamentous (tube-like strands called hypha (singular) or hyphae (plural) • mycelium = aggregate of

hyphae • multicellular, such as mycelial

cords, rhizomorphs, and fruit bodies (mushrooms)

HUMANS AND FUNGI• Beneficial Effects of Fungi

• Decomposition - nutrient and carbon recycling • Biosynthetic factories. Can be used to produce drugs, antibiotics, alcohol,

acids, food (e.g., fermented products, mushrooms) • Model organisms for biochemical and genetic studies• Food• Long historical use of psychoactive fungi for spiritual purposes; modern use as

entheogens and treatment of psychiatric disorders and addiction

• Harmful Effects of Fungi • Destruction of food, lumber, paper, and cloth • Animal and human diseases/infections, allergies • Toxins produced by poisonous mushrooms and within food (e.g., grain, cheese,

etc.) • Plant diseases

FUNGAL CHARACTERISTICS • Cell wall composed of cellulose and/or chitin • Food storage - generally in the form of lipids and

glycogen • Eukaryotes - true nucleus and other organelles

present • All fungi require water and oxygen (no obligate

anaerobes). • Fungi grow in almost every habitat imaginable, as

long as there is some type of organic matter present • Number of described species - between 69,000 to

100,000 (estimated 1.5 million species total)

FUNGAL INFECTIONS• Mycoses – fungal infections• Chytrid fungus – Chytridomycota = fungal group of unusual, very primitive

fungi that may grow as single cells or colonies of cells• Most Chytrids do not form hyphae or yeast-like cells; often have

flagellated spores called “zoospores” • Typically free-living saprobes found in soil, water, decaying organic

material• Some are parasites of plants, animals, and other microbes• Not known to cause human infections, but responsible to wiping out huge

populations of amphibians around the world• Ringworm – dermatophytosis – human skin fungal infection• Some human fungal diseases may be systemic – histoplasmosis

FUNGAL LIFESTYLES•Heterotrophy - 'other food' • Saprophytes or saprobes - feed on dead tissues or organic waste (decomposers)

• Symbionts - mutually beneficial relationships between a fungus and another organism

• Parasites - feeding on living tissue of a host.  • Parasites that cause disease are called pathogens.

FUNGAL INTERACTIONS

FUNGAL DECOMPOSITION

• Fungi get carbon from organic sources• Hyphal tips release enzymes• Enzymatic breakdown of substrate• Products diffuse back into hyphae• Hyphae: tubular, hard cell wall of chitin• Multinucleate• Grow at tips

HYPHAL GROWTH FROM SPORE

MYCORRHIZAE• “Fungus roots”• Mutualism between:

• Fungus (nutrient & water uptake for plant)• Plant (carbohydrate for fungus)

• Several kinds• Zygomycota – hyphae invade root cells• Ascomycota & Basidiomycota hyphae invade root but don’t penetrate cells

• Extremely important ecological role of fungi!

LICHEN• Mutualism between• Fungus – structure and• Alga or cyanobacterium – provides food

• Three main types of lichens: • Crustose lichens form flat crusty plates 

• Foliose lichens are leafy in appearance, although lobed or branched structures are not true leaves

• Fruticose lichens are even more finely branched, may hang down from branches or grow up from ground

• Lichens - nature’s biological monitors of pollution and air quality• Some species more sensitive to pollution• Which species are present can indicate air quality• Most resistant species can also be analyzed for

pollutants, including bioaccumulation of heavy metals and radioactive isotopes

FUNGI APPLICATIONS• http://www.ted.com/talks/

paul_stamets_on_6_ways_mushrooms_can_save_the_world.html

PHILOSOPHY OF SCIENCE AND EVOLUTION PRIMER

• “Neuroscientists have traced subjective feelings of pleasure to endorphins and enkephalins, two groups of neuropeptides produced by the brain. The pleasure associated with seeing beauty, including scientific ‘truth,’ may have come about during the course of evolution, just as love and biophilia – the pleasure we take in the company of others and living creatures – provoke us to seek out mates and the natural environments that have been most conductive to our survival… there may be no better measure of ‘truth’ than that which works – that which helps us survive.” – Margulis and Sagan