MOST FUNGI ARE DECOMPOSERS

• FUNGI ABSORB MATERIALS FROM THE ENVIRONMENT

• INCLUDE MUSHROOMS, MOLDS, & YEAST

• CAN BE HELPFUL OR HARMFUL TO OTHER ORGANISMS

Absorb Material from Environ.• Most are decomposers

that absorb nutrients & leave behind simpler compounds.

• Are heterotrophs (get energy from living or once living matter).

• They and bacteria decompose leaves, shed skin, animal droppings, etc.

• Except for yeast, most fungi are multicellular.

• Typical fungus made of reproductive body & network of cells forming threadlike hyphae (one cell thick). A mass of hyphae form a mycelium. The cells release chemicals, digesting surrounding materials & absorbing nutrients.

• Fungi reproduce sexually (with spores) or asexually. Spore = one reproductive cell that can grow into new fungus.

Absorb Material from Environ.• A single mushroom can make

a billion spores. • Spores are released into air &

spread by wind long distances.• Some spore have tough

coverings protecting them for years until conditions are right for growing.

• Fungi can reproduce asexually when hyphae break off to form anew mycelium. Yeast (single cell fungi) reproduce by cell division, budding & spores.

Mushrooms, Molds & Yeast

• One mushroom may be from a mycelium that fills the size of a football field.

• Some mushrooms are poisonous & some edible. The cap is where spores are made, and hyphae fill the cap & stalk.

• MOLDS: fuzzy growth sometimes seen on food; hyphae grow into food & digest it as they grow.

• Some Penicillium mold are used in Brie & blue cheese. Some aspergillus mold is used in soy sauce. Trichoderma mold grows in soil & makes digestive chemicals used to give blue jeans a stonewashed look.

Mushrooms, Mold, & Yeast• Molds may cause disease. Fungal molds cause athlete’s

foot; others affect plants (Dutch elm); Penicillin is an antibiotic from Penicillium fungus.

• Molds reproduce via spores mostly carried by air; the “hat thrower” fungus Pilobolus grows in animal droppings & shoots off its spore cap via water pressure to land a few feet away to hopefully be eaten in the grass by a cow.

Mushrooms, Molds & Yeast• Yeasts are single

celled fungi. Grow in moist environments (plant sap, skin, shower curtains)

• If yeast growing on human skin reproduces too rapidly, it may cause disease.

• Used in food products (breaks down sugars making CO2 gas to make bread rise & give wine/beer its bubbles).

Fungi can be Helpful or Harmful

• Fungi & bacteria are Earth’s decomposers (even live in sea to recycle materials for ocean-living organisms).

• Hyphae grow into & decompose other organisms material (to turn dead tree back into useful nutrient rich soil or to kill off Dutch elm)

• Most hyphae surround plant roots providing nutrients for plant, while plant provides food.

• Lichen = fungal hyphae mixed around single celled algae. Lichen live in arctic & desert, even bare rock, eventually breaking it down into soil.

Helpful/Harmful Fungi• May make toxins (In

1845 fungus infected Ireland’s potato crop, dropping causing Ireland to go from 8 million to 4 million people; many died of disease, starvation and others left, many to US. Today, many banana crops are being destroyed by fungal disease.

• Penicillin from a fungal toxin kills off many types of bacteria, so is used as an antibiotic.