MICROBIOLOGY

1. MYCOTOXINS: FUMONISINS &
TRICHOTHECENES
PRESENTED BY:
Mousami Jaria
St. George College of Management and Science
MSc Microbiology
Semester 2

2. FUMONISINS
• They are produced by Fusarium spp. on corn
and other grains .
• Certain diseases of humans and animals are
associated with the consumption of grains and
grain products that contain high levels of
these molds.
• The spp. Includes F. thapsinum, F. globosum,
F. moniliforme, F. proliferata etc.

3. Fusarium

4. • F. moniliforme was the first to be associated
with mycotoxins .
• There are atleast 15 fumonisins with the best
known being:
a. FB1
b. FB2
c. FB3
d. FB4
e. FA1
f. FA2
g. FA3

5. CHEMICAL STRUCTURE

6. • The major ones are FB1- FB3 and the others
are considered to be minor.
• FB1 also called macrofusin is produced in
largest quantities by producing strains.

7. GROWTH AND PRODUCTION
• The optimum growth temperature and pH , the
maximum yield of FB1 by strain of F . moniliforme
in cultured occurred in 13 weeks at 20 degree
celcius with a yield of 17.9 g/kg dry weight.
• The optimum time and temperature for FB1
production was 7 weeks at 25 degree celsius.
• Good growth by F. moniliform strain at 25-30
degree cecsius over the pH range of 3 – 9.5 has
been demonstrated.

8. • Little growth occurs at 37 degree celcius over
same pH
• Culture media were used with acidic pH values
adjusted with phosphoric acid.
• The preservative compounds benzoic acid
,BHA, and carcinol have been shown to inhibit
or retard the mycelial growth of number of
Fusarium spp with benzoic acid being more
effective.

9. PREVALENCE IN FOOD
• Leukoencephalomalacia (LEM ) in horses ,
pulmonary edema (PE) of porcines and
esophageal cancer ( EC) in humans occur in
the areas of the world where high levels of
fumonisins are found in grain based foods.
• Ex: The highest rate of human EC in southern
Africa occurs in Transkei where high levels of
FB1 and FB2 are found in corn.

10. INFECTED CORNS FROM FUMONISIN

11. PROPERTIES
• FB1 and FB2 differ only by FB1 having an –OH
group on carbon 10.
• These toxins do not possess cyclic or ring
groups
• They are water soluble
• They are heat stable.

12. PATHOLOGY
• The liver is pr. Target of FB1 in animals.
• In study using rats for over 26 month period
animals either died or were killed after 18
months had micro and macro nodular cirrhosis in
liver.
• LEM was reproduced in horse by the intravenous
injection which spread over 10 days.
• EC in humans is related to high levels of FB1 and
FB2 in Transkei in Africa.

13. TRICHOTHECENES
• They are a very large family of chemically
related mycotoxins produced by various spp of
Fusarium, Myrothecium, Trichoderma,
Trichothecium
• They are a class of sesquiterpenes ( class of
terpenes that consist of three isoprene units.)
• They are produced on many different grains
like wheat ,oats, maize by various Fusarium
spp such as F. graminearum, F. poae .

14. Trichoderma

15. CLASSIFICATION
• Trichothecenes are a group of over 150
chemically related mycotoxins.
• There are four groups of trichothecenes :
• Type A , Type B, Type C, Type D .
• Type A : these trichothecenes have hydroxyl,
ester or no functional group substitutions
around the core ring structures. Ex:
neosolaniol, T-2 toxin.

16. • Type B: They are classified by the presence of
carbonyl functional groups substituted around
core ring structures. Ex: nivalenol, trichotecin.
• Type C :They have an extra C-7, C-8 epoxide
group. Ex: crotocin.
• Type D: They have an additional ring between
C-4 and C-15. These rings can have diverse
additional functional groups.

17. CHEMICAL STRUCTURE

18. FOOD AND CONTAMINATION
• Hazardous concentrations of trichothecenes
have been detected in corn , wheat , barley,
oats, rice, rye and other crops.
• Crop diseases include seed rot, seedling blight,
root rot, stalk rot, ear rot.
• Trichothecenes are also common
contaminants of poultry feeds.

19. SEED ROT SEEDLING BLIGHT

20. DISEASES
• Akakabibyo a disease of similar type has been
associated with trichothecenes contaminated
grains in Japan.
• In China cereals or their products
contaminated with trichothecenes including
DON, T-2 toxin, NIV have been associated with
gastrointestinal disorders.

21. TREATMENT
• There are no known antidotes of
trichothecene exposure .
• The first step in most exposure cases is to
remove potentially contaminated clothing and
to flush the sites of exposure thoroughly with
water.
• Fluids and electrolytes can be given to victims
with high levels of gastrointestinal damage to
slower the effects of absorption.

22. • Onset of leukopenia or reduction of white
blood cell count can be treated with plasma or
pletelet transfusion.
• Hypotension can be treated with
norepinephrine or dopamine.

23. THANK YOU