Physiology of fungi

1. PHYSIOLOGY OF FUNGI
FUNGAL TOXINS, ANTIBIOTICS
By
Cathy Surya
1st Msc Botany
To
Dr. Arya P Mohan
Department of Botany
St. Teresa’s college, Ernakulam
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2. OVERVIEW
• Secondary metabolic pathways - 3
• Mycotoxins - 4-5
• Aflatoxins - 6 -7
• Amatoxins - 8
• Ergot - 9
• Fusaric Acid - 10
• Antibiotics - 11-12
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3. SECONDARY METABOLIC PATHWAYS
• Polyketide Pathway -
Precursor - Acetyl Coenzyme A carboxylases to Malonyl Coenzyme A
The products - greisofluvin, aflatoxins, patulin.
• Isoprenoid Pathway -
Precursor – Acetyl Coenzyme A condensate to Mevalonate.
The products - Several sterols
• Shikimic acid pathway is also another important pathway.
• The products - Aromatic aminoacids ( tryptophan,tyrosine)
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4. MYCOTOXINS
• Mycotoxin - Toxic secondary metabolite produced by several fungus.
• These toxins are hazardous.
• Grow on different crops and foodstuffs (cereals, nuts, spices, dried fruits etc) under warm and
humid conditions.
• Most common mycotoxins - Aflatoxins, patulin, fusarin, amatoxins
and Ergot.
• Most Fungi are aerobic and are almost found everywhere.
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5. MYCOTOXINS
• Reason- Improper storage of food and feed products.
• Some toadstools contain deadly toxins, the classic examples:
Death Cap
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Amanita phalloides Amanita virosa.
Destroying Angel

6. AFLATOXINS 6
Found On
Agricultural crops such as
maize (corn), peanuts,
cottonseed, and tree nuts.
Produced By
Aspergillus species,
A. flavus and A.
parasiticus.
Abundant In
warm and humid regions
of the world

7. • Types – B1,B2,G1 and G2.
• Aflatoxin B1, the most toxic
• Mechanism of Toxicity
• Aflatoxin are specifically target the liver organ.
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Early symptoms of toxicity of liver
fever, malaise and anorexia followed
with abdominal pain, vomiting, and
hepatitis.
In case of Children
stunted growth, delayed development,
liver damage and liver cancer.
High level of aflatoxin exposure
produces an acute hepatic necrosis,
resulting later in cirrhosis.

8. AMATOXINS 8
Mainly found in
mushrooms
Interfere with protein
synthesis, cause liver
failure
highly stable and
resistant to heat
Have no distinct taste or odor,
indistinguishable in color or
appearance from edible
species.
Target the liver and
inhibit transcription
There is no known
antidote.
The stomach can be
emptied after ingestion if
no more than 2 hour
have passed.

9. ERGOT
9
Found on Claviceps
purpurea.
Can affect the nervous,
digestive or
cardiovascular system,
constricting the blood
vessels.
Can lead to
gangrene,
which is when
tissues die
due to a lack
of oxygen.
• Used to relieve some
types of migraine and to
control hemorrhaging
after childbirth.

10. FUSARIC ACID 10
Produced by
Fusarium species - Fusarium
moniliforme, Fusarium
oxysporum, Fusarium
heterosporum
contaminates maize and
other agricultural foods
Disease Symptoms
Interveinal necrosis and
foliar desiccation.
Used to inhibit cell proliferation
and DNA synthesis.
Used to test resistance to itself in
plants

11. Antibiotics
• Some fungi produce substances which help to cure diseases caused by pathogenic micro
organisms. These substances are called the antibiotics.
• The role of fungi in producing antibiotic substances was first established by Sir Alexander
Fleming in 1929.
• First widely used antibiotic Penicillin.
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12. 12
Penicillin- Extracted from
penicillin notatum
(Wonder Drug of World War
II)Used aginst pneumonia,and
other infections.
Some
Antibiotics
Streptomycin- Extracted
from Streptomyces griseus
Used in the multidrug
treatment of pulmunory
tuberculosis.
Griseofulvin- Obtained from
mycelium of Penicillium
griseofulvum . Used to treat
athlete’s foot and other skin
infections.
Ergot is the sclerotium
produced in the ovaries of the
flowers of grasses (rye)
infected with
Claviceps purpurea
Cephalosporins- A natural
product of Cephalosporium
acreminium
Used against skin
infection,resist bacteria etc

13. REFERENCES
• Deacon J.W, Fungal Biology(2005), Institute of Cell and Molecular Biology, University of
Edinburgh, UK, Blackwell publishing, 133-139.
• K.P Nancy, Fungal secondary metabolism: regulation, function and drug discovery(2019),
Nat Rev Microbiol.
• L.D Arnold & M. Evan, Production of valuable compounds by molds and Yeasts(2017), the
journal of antibiotics.
• https://as-botanicalstudies.springeropen.com/
• https://www.ncbi.nlm.nih.gov/
• https://pubchem.ncbi.nlm.nih.gov/
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THANK YOU