ECONOMIC IMPORTANCE
OF FUNGI
ECONOMIC SINGNIFICANCE OF FUNGI
Activities of fungi have great economic
importance
> food processing
> brewing – alcoholic drinks
> as food
> pharmaceutical products – antibiotics / drugs
> plant growth regulators
> vitamins
> enzymes
Food Processing
- improving the texture, digestibility, nutritional
value, flavour or appearance of the raw materials
used
Bread
- using baker’s yeast > Saccharomyces cerevisiae
- bread dough > combination of flour, water, yeast, salt
- mixing process (kneading) > to ensure distribution of
the ingredients and increases elasticity and extensibility
- the dough is left for a few hours > yeast ferments sugar,
producing carbon dioxide (inflates the dough) and
ethanol (driven off during baking)
Soya bean products
- have high protein content
- some less attractive features
- contain a variety of unpleasant compounds (some toxic
and antagonizing nutrient utilization) and some causing
excessive gas production in the gut
- through fermentation > yielding harmless, nutritious and
palatable soya bean products
- soya sauce and tempeh
Soy sauce
- the substrate (cooked soya bean) are inoculated
with Aspergillus species
- using spores of A. oryzae, A. ramarii, A. sojae and
all members of the Aspergillus flavus-oryzae series.
Tempeh
-treatment of soya bean > soaking, removing the seed
coat and cooking
- after draining, mixed with inoculum of Mucorales,
mainly Rhizopus (R. oligosporus) > grow through and
on the surface
Tempeh
Rhizopus sp. starter culture
Cheese and Fermented Milk
- main microorganisms are lactic acid bacteria >
ferment lactose in milk and produce a range of
other metabolites responsible for flavour
- fungi > an important but subsidiary role
Cheese:
- surface-ripened cheese surface-ripened cheese
- blue-vein cheese
blue-vein cheese
Surface-ripened cheese:
- Brie and Camembert
- the surface is sprayed with spores of Penicillium
camemberti
- salt and acid-tolerant yeasts and mitosporic fungus,
Geotricum candidum develop on the surface
- the white mycelium does not penetrate the interior of
the cheese
Penicillium Geotricum
camemberti candidum
- proteolytic enzymes from the fungus diffuse into
the curd and breakdown protein into peptides and
amino acids, causing softening and runniness
- deamination of amino acids by Geotricum >
produces traces of ammonia and contribute to
flavour
- Penicillium > makes lipases which release fatty
acids > contribute to flavour
Blue-vein cheese
- Roquefort, Gorgonzola, Stilton and Danish Blue
- inoculum of Penicillium roqueforti spores is either
included in the starter culture of fresh curd
- the cheese is spiked, air enters allows the germination
of spores
- mycelium grow along the perforations and through the
cavities in the cheese
- blue colouration > production of the spores
- the fungus produces proteolytic and lipopytic enzymes
> the flavour
spore
Penicillium roqueforti
Production of Alcoholic Beverages
The basis of the production of alcoholic beverages :
- under aerobic conditions, yeasts metabolize sugar to
carbon dioxide and water
- if oxygen is scarce or absent, or sugar concentration
is high > fermentation occurs > production of ethanol
and carbon dioxide
Production of Alcoholic Beverages
- fungi > yeast – Saccharomyces cerevisiae, S.
carlsbergensis, S. ellipsoideus
- wine > fermenting plant juices rich in sugars (grapes)
- beer > plant materials rich in starch (barley, hops)
- whiskey > fermented grains (corn, wheat, barley, rye)
Fungi for Food (Mycophagy)
- edible fungi
- some are cultivated to yield fruit bodies (mushroom)
Common edible fungi (mushroom):
- Agaricus bisporus / A. brunnescens (button mushroom)
> in nature – occurs on manure heaps, garden waste and
at the roadsides
Agaricus bisporus
Pleurotus ostreatus (oyster mushroom)
> forms overlapping clusters of large,
sessile basidiomata on dead or dying trees
Lentinus edodes
> shii-take (Japan), xiang-gu
(China)
> in nature – grows on dead wood
of oaks, chestnut
Volvariella volvacea
- paddy/rice straw mushroom
- has been cultivated for centuries
> usually harvested and canned in
immature condition (before the cap
expands)
Flammulina velutipes
- enokitate (Japan)
- winter / velvet stem mushroom
- has long narrow stipes with tiny
caps
Auricularia polytrichia
- tree ear / jelly fungus > ear-like
basidiomata
- grows on dead trees
Tricholoma matsutake
- matsutake or pine mushroom
(Japan, Korea)
- highly prize mushroom
- thought to be the best of all
edible mushroom
Tuber sp.
- highly prized as food
- subterranean mushroom
- ectomycorrhizal fungi > found in close
association with tree roots
Tuber magnatum
Tuber melanosporum
Truffle
hunting
There are no simple ways of distinguishing between
the edible and poisonous fungi.
Only eat a known edible fungi.
Utilization of Fungal Metabolites
- primary metabolites > those that have to be
produced for growth to occur
- secondary metabolites > those that are not
essential for vegetative growth, often associated
with differentiation and sporulation
Primary metabolites
Ethanol
- as industrial alcohol > commercially important
chemical
- produced by fermentation
- fermentation generally carried out with
Saccharomyces cerevisiae, Schizosaccharomyces
pombe
- major substrate is sugar cane juice, starchy
materials (grain, potatoes and cassava)
Primary metabolites
Citric acid
- main organism used > Aspergillus niger
- main carbon source – molasses from refining
of cane or beet sugar
- application > food, beverages, pharmaceutical
Aspergillus niger
Enzymes
- extracellular enzymes > breakdown polysaccharides
and proteins into sugars and amino acids > assimilated
- utilize in numerous industrial processes
- amylase > Aspergillus niger
> hydrolysis of starch to dextrin and sugar
> clarify fruit juices
- invertase > S. cerevisiae
> hydrolysis of sucrose to glucose and fructose
> candy making / confectionery
- cellulases > Trichoderma
- hydrolyze cellulose to cellobiose
- food processing
- proteases / protoelytic enzymes > Aspergillus
species / A. oryzae
> mixture of enzymes that breakdown proteins
> softening of leather, liquid glues, stain-removers
in detergents
- pectinase > Aspergillus species
> clarify fruit juices, linen making
- lipase > A.niger, A.oryzae, Rhizopus
> hydrolyzes lipids to glycerol and fatty acids
> improve flavor of processed food
> boost cleaning reaction of detergents
Secondary metabolites
Antibiotics
- most studied secondary metabolites
- penicillin > mostly are produced by species of
Penicillium
- cephalosporin > Cephalosporium acremonium
- griseofulvin (skin infection) > Penicillium
griseofulvum
Penicillium Cephalosporium
Pharmacologically active products
Cyclosporine A
- immunosuppressive drugs > reducing
incidence of organ rejection
- use in treatment of psoriasis and eczema
- Tolypocladium inflatum
Pharmacologically active products
Statins
- cholesterol lowering properties
- red yeast rice > product of yeast (Monascus
purpureus) grown on white rice.
Pharmacologically active products
Statins
- cholesterol lowering properties
- mevastatin > Penicillium citrinum
Penicillium citrinum
Vitamin production
Vitamin B2 (riboflavin)
- Ashbya gossypii
- animal feed and human nutrition
Vitamin D
- S. cerevisiae
- fortification of food and feed
