Fungi grow without sunlight and feed on organic matter. A
typical fungus is made of many threads growing on or in a food source. Each
thread, called a hypha, oozes chemicals that break down the food. This releases
nutrients that the hyphae can soak up. Fungi include MOULDS,
mushrooms, toadstools, puffballs, and truffles. About one in four fungi lives
in partnership with an alga – these partnerships are called LICHENS.
Hyphae branch to form a network called a mycelium. The combined
surface area of all the hyphae allows the fungus to digest and absorb a lot of
food. Many fungi play a vital role in food webs. Their digestive action is the
first step in breaking down dead plant and animal matter, making it useful to
other life forms.
Grapes often have a fine coating of yeast. Yeasts are a type of
fungus which grows in colonies of single cells. They thrive where there is a
good supply of sugar, such as on the surface of fruit. As yeasts consume sugars
they can create a toxic by-product that people value – alcohol. Yeasts
are essential for producing alcoholic drinks, such as wine.
Fungi produce fruiting bodies, such as puffballs, which we can see
above ground. These fruiting bodies release tiny spores that are carried in the
air and start to grow wherever they fall. A single fruiting body can produce
millions of spores, so it is likely that some will land on a suitable food
source.
Fungi called moulds do not produce large toadstools.
Their tiny fruiting bodies look like peppery spots and are usually black or
blue. Mould grows wherever spores land on suitable food, such as bread or
fruit. The mould’s threads, or hyphae, give it a woolly
appearance.
Greenish Penicillium mould grows outwards
across the surface of a dish of nutrient gel. This mould releases a chemical
called penicillin, which is an antibiotic. Antibiotics are used to kill
bacteria that cause diseases, without causing harm to the organism or person
infected with these bacteria. Moulds are now grown in huge vats to produce this
medicine.
BIOGRAPHY: SIR ALEXANDER FLEMING Scottish, 1881-1955
In 1928 Fleming discovered medicine’s first antibiotic,
penicillin, which has since saved millions of lives. He had noticed that one of
his laboratory dishes of bacteria was infected with a mould. Around the mould,
the bacteria had disappeared. Fleming realized that the mould produced a
substance that killed bacteria.
Some fungi can combine with algae to form structures
called lichens. Lichens can be flat or fluffy, living on rocks and tree trunks,
and in environments too harsh for plants. They are often the first organisms to
colonize a tough new habitat, such as a building’s roof or
walls.
Both the fungus and the alga benefit from living together as a
lichen. The green alga photosynthesizes and makes sugar, some of which it gives
to the fungus. In turn, the fungus gathers up nutrients and moisture and passes
them to the alga. This type of two-way relationship between life forms is
called symbiosis.
