Aspergillus flavus is of ubiquitous occurrence in nature.Apergillus flavus is widely distributed in nature and a mean to cause Food Poisoning.
Since the discovery of aflatoxins, it has become the most widely reported food-borne fungus, reflecting its economic and medical importance, and ease of recognition, as well as its universal occurrence. A. Flavus is the most common species in peanuts and the second most common in corn.
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A. parasiticus if less widely distributed as campare to A. Flavus .A. parasiticus have similar growth patterns as A. Flavus .Growth occurs at a pH ranging from 2 to 10.5. growth temperatures of 32-33 ºC and can growth at 10-42 ºC, Aflatoxins are produced at 12-40º C.
Aspergillus ochraceus is a widely distributed mould, particularly common on dried foods. It is xerophile, it grows at temperatures of 8 to 37 C and within a wide pH range of 2.2 to 10.3. Ochratoxin A is produced at quite high temperatures between 25 and 30 C.
The natural habitat for A. ochraceus and the other closely related species is drying or decaying vegetation, seeds, nuts and fruits. A. ochraceus is widely distributed in foods, especially dried foods, with records from such diverse sources as various kinds of beans, dried fruit, biltong and salt fish , including peanuts, pecans and betel nuts, are also a major source. Although A. ochraceus has been isolated from a wide range of cereals, including barley, wheat, flour and rice, records are rather infrequent.
Aspergillus versicolor is a slow-growing filamentous fungus.The most important species in the "Aspergillus versicolor group". commonly found in damp indoor environments and on food products. It is widely distributed in foods particularly stored cereals, cereal products, nuts, spices and dried
meat products. The reported minimum temperature for growth is 9 C at aw 0.97 and the maximum temperature is 39 C at a w 0.87.
It is a thermophile with a temperature range for growth of between 10 and 55 C and an optimum
between 40 and 42 C. It is one of the least xerophilic of the common aspergilla.It is best found in decaying vegetation, in which it causes spontaneous
heating.It is best recognized as a human pathogen causing aspergillosis of the lung. It is isolated frequently from foods particularly stored commodities.
Aspergillus terreus occurs commonly in soil and foods particularly stored cereals and cereal products,beans, pulses and nuts. Produces rapidly growing pale brown colonies, with Aspergillus heads bearing densely packed metulae and phialides with minute conidia borne in long columns.
It is found in soil and decomposing plant materials and is easily recognizable by its large
blue-green club-shaped heads. It is especially common in malting barley
All Eurotium species are xerphilic. E. Repen are one of important spoilage moulds in all types of stored commodities like stored grains, spices, nuts and animal feeds.An ascomycete characterized by whitish to bright yellow spherical fruiting bodies (cleistothecia) containing spherical asci which in turn each enclose eight colourless ascospores.
Classification of the penicillia is based on microscopic morphology. The genus Penicillium is divided into subgenera based on the number and arrangement of phialides and metulae and rami on the main stalk cells.
P. citreonigrum is not a commonly isolated species, but it is widely distributed.P. citreonigrum grows in rice after harvest, when the moisture content reaches 14.6%. At 1% higher moisture, other fungi will overgrow it, so the moisture band for invasion is narrow. The fungus is reported to be favoured by the lower temperatures and shorter hours of daylight occurring in the more temperate rice growing areas. The Oriental disease known as "beriberi" has traditionally been regarded as a nutritional disease, an avitaminosis. However, beriberi is more than a single disease, and one form of it, known in Japan as acute cardiac beriberi, has been established to be a mycotoxicosis. Acute cardiac beriberi in Japan is now only of historical interest. However, P. citreonigrum and Citreoviridin may still occur in other parts of Asia. Citreoviridin is also produced by P. ochrosalmoneum
P. citrinum has been a well recognised species for most of this century. Its importance in the present context lies not so much in the production of a mycotoxin of particular human significance, but in its ubiquity, so that any toxins produced can be expected to be very widely distributed in food and feed supplies. P. citrinum is the major producer of citrinin,
Fusarium is one of the most important genera of plant pathogenic fungi on earth, with a record of devastating infections in many kinds of economically important plants. Fusarium species are responsible for wilts, blights, root rots and cankers in legumes, coffee, pine trees, wheat, corn, carnations and grasses. The importance of Fusarium species in the current context is that infection may sometimes occur in developing seeds, especially in cereals, and also in maturing fruits and vegetables. An immediate potential for toxin production in foods is apparent.
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