Microbiology

CME - Aflatoxins

1. Name two fungal species producing aflatoxins .
The aflatoxins are a group of structurally related toxic compounds produced by certain strains of the fungi Aspergillus flavus and A. parasiticus.

2. The most severe contamination occurs in which food/feeds?
The most pronounced contamination has been encountered in tree nuts, peanuts, and other oilseeds, including corn and cottonseed.

3. Which is the most predominant and toxic aflatoxin ?
Aflatoxin B1 is usually predominant and is the most toxic.

4. How are the aflatoxins designated ?
The major aflatoxins of concern are designated B1, B2, G1, and G2.

5. Which aflatoxins fraction is excreted in the milk of dairy animals which have consumed aflatoxins contaminated food?
Aflatoxin M a major metabolic product of aflatoxin B1 in animals and is usually excreted in the milk and urine of dairy cattle and other mammalian species that have consumed aflatoxin-contaminated food or feed.

6. Which system of the body do these aflatoxins affect?
Aflatoxins produce acute necrosis, cirrhosis, and carcinoma of the liver

7. Which of the aflatoxins is a potent carcinogen?
Aflatoxin B1 is a very potent carcinogen in many species

8. Which country has reported aflatoxicosis in humans?
One of the most important accounts of aflatoxicosis in humans occurred in more than 150 villages in adjacent districts of two neighboring states in northwest India in the fall of 1974.

9. What was the source in this outbreak?
Contaminated corn

10. Aflatoxicosis was initially called by which name?
In the 1960 more than 100,000 young turkeys on poultry farms in England died in the course of a few months from an apparently new disease that was termed "Turkey X disease". They were all associated with feeds, namely Brazilian peanut meal.

11. How is the name aflatoxin derived?
The toxin-producing fungus was identified as Aspergillus flavus (1961) and the toxin was given the name Aflatoxin by virtue of its origin (A.flavis-> Afla).

12. Why are the aflatoxins designated as B,G or M?
The aflatoxins M1 and M2 were first isolated from milk of lactating animals fed aflatoxin preparations ; hence , the M designation . Whereas the B designation of aflatoxins B1 and B2 resulted from the exhibition of blue fluorescence under UV-light , while the G designation refers to the yellow-green fluorescence of the relevant structures under UV-light .

13. What is the relation of AFB to aflatoxin?
Urine samples collected after exposure to alfatoxins were found to contain 2,3-dihydroxy-2-(N7-guanyl)-3-hydroxyaflatoxin B1, trivially known as AFB-Gual .

14. Enumerate food detoxification strategies.
Because aflatoxin contamination is unavoidable, numerous strategies for their detoxification have been proposed. These include physical methods of separation, thermal inactivation, irradiation, solvent extraction, adsorption from solution, microbial inactivation, and fermentation. Chemical methods of detoxification are also practiced as a major strategy for effective detoxification .

15. Name a few other poisonous substances produced by fungi?
Some of the poisonous substances made by fungi, such as alpha-amanitin, and phalloidin from the death cap mushrooms, muscarine from the fly agaric, orellanine from the false chanterelle, and lysergic acid from ergot of rye have been purified and have found scientific and medical uses.

16. Trichothecenes are obtained from which fungus?
Disease of cereals known as "scab" had first been characterized in the 19th Century. The diseases were caused mainly by fungi of the genus Fusarium

17. Approximately how many research papers have been published on aflatoxins?
5000

18. Which other fungal genera produce aflatoxins?
Aflatoxins are produced by different species of Aspergillus, particularly flavus and parasiticus, as well as members of the Genera Penicillium and Rhizopus

19. What were the presenting clinical features of the Indian outbreak?
The illness was characterized by jaundice, rapidly developing ascites, portal hypertension and a high mortality rate.

20. What is Reye's syndrome and how is it associated with aflatoxins?
Reye's syndrome is characterized by symptoms of encephalopathy and fatty degeneration of the viscera. It occurs in children under 16 and is believed to follow nonspecific viral illness, influenza B and varicella. Abnormalities are present in mitochondrial structure and function, including defective oxidative phosphorylation. Aflatoxins have been reported to be associated with a Reye-like Syndrome in Thailand, New Zealand, Czechoslovakia, the United States, Malaysia, Venezuela, Europe.

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