Aspergillus flavus Aspergillus flavus | About Aspergillus flavus | Aspergillus flavus is a fungus. It grows by producing thread like branching filaments known as hyphae. Filamentous fungi such as
A. flavus are sometimes called molds. A network of hyphae known as the mycelium secretes enzymes that break down complex food sources. The resulting small molecules are absorbed by the myceilium to fuel additional fungal growth. The unaided eye cannot see individual hyphae, but dense mats of mycelium with conidia (asexual spores) often can be seen. The ear of maize below shows the growth of the fungus covering four maize kernels. When young, the conidia of
A. flavus appear yellow green in color. As the fungus ages the spores turn a darker green.
In nature,
A. flavus is capable of growing on many nutrient sources. It is predominately a saprophyte and grows on dead plant and animal tissue in the soil. For this reason it is very important in nutrient recycling.
Aspergillus flavus can also be pathogenic on several plant and animal species, including humans and domestic animals. The fungus can infect seeds of corn, peanuts, cotton, and nut trees.
The fungus can often be seen sporulating on injured seeds such a maize kernels as shown above. Often, only a few kernels will be visibly infected.
Growth of the fungus on a food source often leads to contamination with aflatoxin, a toxic and carcinogenic compound. Aspergillus flavus is also the second leading cause of aspergillosis in humans. Patients infected with A. flavus often have reduced or compromised immune systems. 
The epidemiology of
Aspergillus flavus differs depending on the host species. The figure to the left shows the life cycle of the fungus on maize.
Click on image to view larger. The fungus overwinters either as mycelium or as resistant structures known as sclerotia. The sclerotia either germinate to produce additional hyphae or they produce conidia (asexual spores), which can be dispersed in the soil and air. These spores are carried to the maize ears by insects or wind where they germinate and infect maize kernels.
Unlike most fungi,
Aspergillus flavus is favored by hot dry conditions. The optimum temperature for growth is 37 C (98.6 F), but the fungus readily grows between the temperatures of 25-42 C (77-108 F), and will grow at temperatures from 12-48C (54-118 F). Such a high temperature optimum contributes to its pathogenicity on humans.
Aspergillus flavus - Wikipedia, the free encyclopedia Aspergillus flavus is a
fungus. It is a common
mold in the environment, and can cause storage problems in stored grains. It can also be a human
pathogen, associated with
aspergillosis of the
lungs and sometimes causing
corneal,
otomycotic, and nasoorbital infections. Many strains produce significant quantities of
aflatoxin, a carcinogenic and acutely toxic compound.
A. flavus spores are
allergenic.
A. flavus sometimes causes losses in
silkworm hatcheries.
A. flavus is the second most common agent of
aspergillosis, the first being
Aspergillus fumigatus.
A. flavus may invade arteries of the lung or brain and cause
infarction.
Neutropenia predisposes to aspergillus infection.
Aspergillus flavus also produces a toxin (
aflatoxin) which is one of the aetiological agents for
hepatocellular carcinoma.
A. flavus grows as a yellow-green mold in culture. Like other
Aspergillus species it produces a distinctive
conidiophore composed of a long stalk supporting an inflated vesicle. Conidiogenous cells on the vesicle produce the
conidia.
Many strains of A. flavus exhibit a greenish fluorescence under UV light that is correlated with levels of aflatoxin production. A. flavus is particularly common on
corn and
peanuts, as well as
water damaged carpets, and is one of several species of mold known to produce
aflatoxin which can cause acute hepatitis, immunosuppression, and hepatocellular carcinoma. The absence of any regulation of screening for the fungus in countries which also have a high prevalence of viral
hepatitis highly increases the risk of hepatocellular
carcinoma.
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