Types of Mycotoxin

Gaurab Karki — Thu, 27 Aug 2020 03:32:23 +0000

Mycotoxins:

Mycotoxins are toxic chemical produced by some pathogenic strain of fungi.
Many strains of fungi contaminate the food and produce potent mycotoxin in food.
Disease resulting from ingestion of mycotoxin in food is called mycotoxicosis. E.g. mushroom poisoning.
One important characteristic of most mycotoxin is that they are heat stable.
Therefore, if mycotoxin is produced in food, it is not damaged easily during normal cooking of food.
Most of the mycotoxin cause mutation and are associated with various types of cancer.
Mycotoxins are secondary metabolites of fungi.
Metabolites produced by microorganisms are divided into two types i.e. primary and secondary metabolites.
Metabolites produced by certain microorganisms that serve as a growth factor for other microorganisms are called as primary metabolites. E.g. vitamins, amino-acids, carbohydrate etc.
Primary metabolites are produced during log phase.
Metabolites produced by certain microorganisms which are not needed for growth if other organisms are called secondary metabolites. E.g. toxin, antibiotic etc.
Secondary metabolites are produced during stationary phage of growth.

It is produced by Aspergillus flavus, A. parasiticus and some Penicillium spp.
It is located from variety of mold contaminated food like peanuts, rice etc.
Two major types of toxin include B₁ and G₁ that show blue and green fluorescence when exposed to UV lights.
Other types of aflatoxin include B₂, G_2,M₁, M₂, and P₁ which are derivatives of B₁ and G_1.
Among them B₁ is most toxic.
After ingestion, aflatoxin binds to chromosomal DNA and causes point mutation and frame-shift mutation.
By inducing mutation, they cause cancer of liver.
Aflatoxin is toxic to wide variety of animals like cat, chicken, cattle, human beings etc.

It is produced by wide variety of mold including Penicillium expansum, P. patulum, P. melini, P. equinum, Aspergillus clavatus, A. terreus etc.
It is isolated from many molds contaminated food like bread, sausages, fruits etc.
It is white crystalline solid.
It is sensitive to SO₂ and alkali but resistant to acid.
Patulin binds to NH₂ and -SH functional group of biomolecules and causes chromosomal aberration.
It affects wide variety of animals and plants as well as bacterial cells like E. coli and Staphylococcus aureus.
Therefore, originally it was classified as antibiotics.
Tissue damage caused by patulin include oedema of brain, hemorrhage of lungs, damage of blood capillary, spleen and kidney.

It is produced by Penicillium roqueforti, P. cyclopium, P. morteneii, Aspergillus flavus, A. ochraceus.
It is isolated from many molds contaminated food like tobacco.
Penicillic acid binds to –SH and –NH₂ group of biomolecules forming covalent bond.
It is carcinogenic and affects wide variety of animals including rat.

It is produced by Penicillium citrinum, P. viridicatum and other species.
It is isolated from many mold contaminated foods like- polished rice, bread, meat and meat products
It is carcinogenic to wide variety of animals.

There are atleast seven types of structurally related ochratoxin, of which type A is the most common and most toxic.
It is produced by many Aspergillus and Penicillium species like- A. ochraceus, A. alliaceous, A. mellis, P. viridicatum, P. cycloplum.
Like other mycotoxin, it is heat stable and is not damaged during cooking of food.
When ochratoxin is ingested it induces mitosis and cause cancer of kidney.