Fungi play a significant role in our daily life. They are our greatest friends as well as foes.
➢Some fungi are prized for their usefulness to mankind, while others are highly injurious as they are responsible for several disease in plants, animals and human beings.
➢ Some important useful and harmful activities of fungi are discussed below:
I. Useful activities:
Fungi are beneficial to us, directly or indirectly in many ways. They clean our environment by removing organic dyes; they provide food medicines and several other useful products. Fungi also play role in many industries.
A. Fungi as Food
Many edible fungi are of great economic value as food. They
are regarded as delicacies of the
table. There are said to be over 200 species of edible
fungi.
Mushrooms: Fleshy fruiting bodies of higher Fungi.
➢Some mushrooms are edible –
contain high amounts of proteins, vitamins, carbohydrates,
minerals, dietary fiber , amino acids etc.
- Agaricus campestris (Field Mushrooms)
- Clavatia
- Coperinus
- Lentinus
- Torulopsis
- Pleurotus ostreatus (Oyster mushrooms)
- Agaricus bisporus (Button mushroom)
- Volvariella volvacea (Paddy straw mush room)
- Morchella esculenta (Morels)
- Tuber melanosporum (Black truffle)
Fungi as Single Cell Protein (SCP)
Dried biomass of certain fungi are consumed as a protein
source.
➢ Single cell protein (SCP)
obtained from Yeast, species of Aspergillus, Penicillium,
Fusarium, Neurospora and Candida is a complete substitute
for conventional protein food.
➢Quorn , a meat substitute
product contain mycoprotein as an ingredient , which is derived
from the fungus Fusarium venenatum.
Yeasts: Brewing and Baking
Yeasts are used in breweries and bakeries for fermenting sugar.
Yeast is an Important sources of vitamins B and D complex.
Saccharomyces, Endomyces, Rhodotorula and Torulopsis are
particularly rich in proteins and
hence they are mixed in incomplete livestock.
➢ A popular food Sufu is produced
from species of Mucor and Antimucor.
➢Some foods like soybeans and
cassava although rich in nutrients can not be easily digested
by man. These are made easily palatable by fermenting fungi.
➢Soybeans are fermented by
species of Rhizopus to prepare temeph , a food which is easily
digestible and tasty.
➢ A mixture of yeasts and cereal flour forms a nutritious preparation, called incaparina. Incaparina foods developed by the Institute of Nutrition of Central America and Panama consist of corn(26%), cotton seed flour (38%) , Sorghum (26%), food yeast(3%), minerals and vitamins.
B. Fungi as Medicine
Several fungi are used in the production of medicines
(i) Antibiotics : Antibiotics are metabolic substances
produced by some living organisms
which are injurious to other living beings.
Penicillin - Alexander Fleming in 1944 for the first time
extracted the wonder drug Penicillin
from Penicillium notatum is useful against most of the
pathogenic bacteria.
Cephalosporins -produced from the fungus Cephalosporium
acremonium are used to treat
respiratory tract, skin and urinary tract infections.
Cyclosporin: from the fungus Tolypocladium inflatum is
widely used as an
immunosuppressant and greatly improves the success rate of
transplant operations.
Griseofulvin : produced from Penicillium griseofulvum - used
to treat infections of the skin,
scalp, nails, feet etc.
(ii) Ergot: Ergot is prepared from the sclerotia of
Claviceps purpurea. It contains some
alkaloids which are used to induce uterine contraction for
abortion, in the treatments of
menstrual disorders etc.
iii) Antitumour agents: Shiitake mushroom- (Lentinula
edodes) contain a polysaccharide
lentinan has anti-tumour potential.
Ganoderma lucidum : has polysaccharides that have
anticancerous activity
iv) Vitamins: Vitamins are accessory micro-nutrients, which
are required by living organisms
for their proper growth.
➢ Saccharomyces cerevisiae
produce vitamin B complex .
➢Synthesis of B-group vitamins
by mycorrhizal fungi. The vitamin produced in largest
amounts by the mycorrhizal fungi was thiamin (vitamin B1).
➢ Ergosterol, a precursor of
vitamin D is synthesized by some yeasts and moulds.
(v) Production of Steroids : Steroid like cortisone is
produced by Aspergillus niger from plant
glycosides by fermentation.
C. Fungi in production of Organic acids:
➢The important organic acids
produced commercially as the result of the biochemical
activities of moulds are oxalic acid, citric acid, gluconic
acid, gallic acid, fumaric acid, etc.
- Citric acid : Produced by fermenting sucrose and molasses by Aspergillus niger and A. wentii.
- Kojic acid : Produced by the fermentation of sugars by Aspergillus oryzae
- Itaconic acid : Produced by fermentation of sugars by Aspergillus itaconium, A. terreus
- Gluconic acid : Produced by fermenting sugars by Aspergillus niger and Penicillium purpurogenum.
- Fumaric acid : Produced by the fermentation of sugars by Rhizopus stolonifer.
- Lactic acid, oxalic acid, Succinic acid : Some species of Mucor, Rhizopus etc. are used in the production of Lactic acid, oxalic acid and Succinic acid .
D. Fungi in enzyme Production
Many intra and extracellular enzymes are found in fungi and some are extracted on commercial scale.
Invertase: Yeasts (Saccharomyces cerevisiae) are used for
the extraction of enzyme invertase
which is used to hydrolyse sugars into glucose and fructose. It is used in confectionery and
paper industries.
Zymase: Yeasts , Saccharomyces cerevisiae are used for the
extraction of enzyme Zymase
which is used in the preparation of ethyl alcohol by the
fermentation of carbohydrates.
Amylase: Aspergillus niger and A. oryzae are used for the
production of amylase used in
alcohol industry.
Cellulase: Trichoderma reesei is used for the production of
cellulase used in the
saccharification of cellulosic and lignocellulosic wastes.
➢ Fungi are also used in the
production of other enzymes like lipases, pectinases, and proteases
etc.
E. Fungi plays an important role in agriculture in various ways
Fungi as decomposers :
➢Saprophytic fungi secrete
enzymes and decompose dead remains of plants and animals .
Hence they are called as ‘vegetative vultures of Plant Kingdom.’
➢During this process, complex
organic compounds like cellulose, hemicelluloses, chitin,
pectin, lignin etc. are degraded by fungi and produce humus
, a nutrient rich material .
➢ The humus help to maintain the
physical and chemical properties of soil, increases soil
fertility and promotes various biological activities in the
soil.
Fungi as biocontrol agents:
➢ Some fungi play an important
role in the biological control of pests.
Trichoderma harzianum is used to control the blight of
tomato. Blight of tomato (caused by
Alternaria solani).
➢ Trichoderma harzianum is used
to control the blight of peanut (ground nut) caused by
Sclerotium rolfsii
The fungus Gliocladium roseum is used to control white
mould, Sclerotinia diseases.
➢ Trichoderma lignorum suppresses
the growth of the root rot fungus Pythium.
➢ Growth of Rhizoctonia solani
can be checked by Penicillium vermiculatum
Several fungi are used as important research tools for the
study of various fundamental
biological processes.
➢They grow very fast and require
a short period to complete their life cycle.
➢ Experimentation with fungi
requires less space and inexpensive equipments.
➢Neurospora crassa is used in
genetic studies because it is a haploid organism and make
genetic analysis simple because recessive traits will be
expressed in the offsprings.
➢Analysis of genetic
recombination (Tetrad analysis) is facilitated by the ordered
arrangement ascospores formed after meiosis in the ascus.
➢Several strains of Aspergillus
niger have been used as a test organism for determining
Mg, Cu, Zn and Mo in soils.
➢The slime mold Physarum
polycephalum has been used as a model organism to study
DNAsynthesis, morphogenesis, mitotic cycle, amoeboid
movement, cell motility etc.
G. Nitrogen fixation and Soil formation:
Some yeasts are involved in nitrogen fixation and forms Rhizopus, Aspergillus, Cladosporium etc play an active role in soil formation.
II. Harmful ActivitiesThere are many fungal activities which are harmful to
mankind. Fungi incite many diseases in
plants , animals and human beings.
➢ Fungi cause considerable loss
to food, vegetable and fruit crops.
➢ They destroy valuable timbers
and cause spoilage of foodand many other useful articles
Fungi as Pathogen
A. Plant diseases: Most of the parasitic fungi cause
diseases in plants, especially in flowering
plants. The common fungal diseases of plants are rusts,
smuts, mildews, blights, rots and wilts.
Rust diseases: caused by fungi of the order Pucciniales.
e.g., Wheat stem rust, also known
as black rust, is caused by the fungus Puccinia graminis.
Smut diseases: Caused by the fungus Ustilago. It mainly
infects inflorescence, flowers,
anthers etc. The grains get filled with black powder of
teliospores of the fungi. e.g. Loose smut
of wheat caused by Ustilago tritici
Covered smut of Barley - caused by Ustilago hordei . Grains
are replaced by brown-black
balls.
Powdery mildew:
✓ Powdery mildew is caused by
fungi of the order Erysiphales.
✓Infected leaves get covered
with a white to gray powdery growth. e.g. Powdery mildew of
wheat caused by Erisiphae graminis
✓ Powdery mildew of peas caused
by Erisiphae polygoni .
Blight diseases:
✓Blight diseases are
characterized by a rapid and complete chlorosis , browning and death of
plant tissues such as leaves, branches, twigs or floral
organs.
e.g. Late blight of potato caused by Phytophthora infestans
, the disease which led to the
great Irish famine.
White rust of Crucifers
✓ White rust is a disease in
plants caused by the fungus Albugo candida .
✓Symptoms include chlorosis on
leaf surfaces, white blister like growths on the
underside of leaves and on the stems of the plant, and
swelling of the roots.
Blast diseases
✓Acommon disease of paddy , Oryza
sativa by the fungus Pyricularia oryzae.
✓ Lesions develop on leaf
sheaths and on the stems.
✓ The weakened stems are easily
broken.
B. Animal diseases
Several fungal species live parasitically on animals and
cause various diseases.
Ringworm (Tinea corporis)
✓This is a common fungal skin
infection that looks like a circular rash.
✓Trichophyton, Microsporum, and
Epidermophyton are the most common genera of fungi
that cause ringworm in humans.
Aspergillosis
✓ Aspergillosis is caused by the
fungus Aspergillus.
✓Symptoms include allergic
reactions, lung infections, and infections in other organs.
Candidiasis
✓ Caused by the yeast Candida,
the most common of which is Candida albicans.
✓ Can occur in the mouth and
throat, vagina or blood stream.
Athlete’s foot
✓ Athlete's foot is a fungal
infection caused by Trichophyton rubrum that usually begins
between the toes.
✓It commonly occurs in people
whose feet have become very sweaty while confined within
tightfitting shoes.
✓Symptoms include a scaly rash
that usually causes itching, stinging and burning.
✓ This fungal infection is
called athlete’s foot because it is commonly seen in athletes.
C. Spoilage of Food stuffs
➢Alarge number of food articles,
if not properly stored are spoiled by fungi, like Mucor,
Rhizopus, Aspergillus, Penicillium and yeast.
➢ Species of Mucor and Rhizopus
are commonly seen on the bread and pickle.
➢ Dairy products are spoiled by
the species of Mucor, Oidium, Torula, and Penicillium
➢ Mucor mucedo and Rhizopus
stolinifer spoil frozen meat by causing black spot disease.
➢ Some fungi infect food stuffs
even at a very low temperature, Cladosporium herbaceum
can grow on meat stored at -6 degree Celsius.
➢ Several species of
Aspergillus, Alterneria and Rhizopus cause post harvest disease in fruits
and vegetables thus shortening their storage life.
D. Rotting of wood
➢ Several fungi ( Ganoderma, Polyporus) bring about the degradation of cellulose and lignin and thereby cause the rotting of wood.
E. Damage commercial articles
➢ Fungi like Rhizopus, Aspergillus, Cladosporium etc. cause the deterioration and damage of textile articles, leather, rubber, cork, etc
F. Destrction of Paper pulp
➢ Some species of Polyporus, Polysticus, etc damage wood pulp and thereby seriously affect paper industry.
G. Production of toxins and hallucinogens :
➢ Several fungi produces toxins and hallucinogenic substances (e.g. lysergic acid diethylamide-LSD), which are serously harmful to human beings.