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_t
he_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