1. IDENTIFYING CHARACTERISTICS
The picture to the left shows A. carbonarious.
2. TAXONOMIC DESCRIPTION
Aspergillus is a saprophytic fungus. It was
originally classified as Deuteromycotina, also known as Fungi
Imperfecti. Then, after further research, it was reassigned to
Ascomycotina because of its ability to form asci within closed
ascocarps. This genus has not been subdivided into classes or
orders because the classification of the Ascomycetes is not yet
complete. There are however, over 200 different species of Aspergillus,
some of the more common ones include A.
niger, A. flavus, A. utus, A. terreus, A. carbonarious, and
A. fumigatus.
The picture to the right is of A. terreus.
3. ISOLATION AND ECOLOGY
Species in the genus Aspergillus are found in various habitats and under many different environmental conditions. Aspergillus is abundant in soil, air, and aquatic settings. Indoors it inhabits areas of high humidity like basements and cellars, it thrives on improperly stored foods, and it can live off duct particles rich in oragnic matter. It has been discovered that this genus is one of the most xerotolerant groups of fungi. Apsrergillus can withstand conditions of low moisture and extreme temperatures. This allows it to act as a 'storage fungi' decaying agricultural products and dried foods.
There are a wide range of applications for Aspergillus species. Some strains are used in producing antibiotics and beneficial genetic mechanisms. Aspergillus is widely used in feed fermentation, allowing the commercial exploitation of many products. A. niger is used to make citric acid, a common preservative in soft drinks, most canned goods, and just about any type of shelf food.
Unfortunately, there are some disadvantages associated with this
widespread fungal genus.
Aspergillus
tends to cause spoilage of foodstuffs and can
decompose other materials such as wood, textiles, paint, and
leather. Some species will severely damage agricultural crops,
for example, A. flavus
and A. parasiticus
produce aflatoxins that cause ear rot in corn. Another strain, A.
fumigatus, releases airborne
spores that are potentially pathogenic to humans. If these spores
are inhaled during a period when one's immune system is lowered,
they will suffer increasingly serious allergies and may
eventually contract the disease Aspergillosis.
The picture to the left shows a severe case of corn ear rot caused by A. flavus and A. parasiticus.
4. ADDITIONAL SOURCES OF INFORMATION
Bossche, Hugo Vanden, Donald W. R. Mackenzie, and Geert
Cauwenbergh. Eds. 1987. Aspergillus
and Aspergillosis. Plenum Press. New York, New York. 1-23.
Cole, Gary T. and Robert A. Samson. 1979. Patterns of Development in Conidial Fungi. Pitman. Belmont, California. 58, pp.
Dix, Neville J. and John Webster. 1995. Fungal Ecology. Chapman & Hall. London. 334 -337.
Hawksworth, D. L., P. M. Kirk, B. C. Sutton, and D. N. Pegler. 1995. Ainsworth & Bisby's Dictionary of Fungi. Eighth Edition. CAB Internationsl. Wallingford. 35-38.
Webster, John. 1970. Introduction to Fungi. Cambridge University Press. Cambridge. 202-204.
5. LINKS TO OTHER SITES ON ASPERGILLUS
The Aspergillus Research Page is full of useful information about this particular genus.
To find the ingredients used to make media for A. nidulans cultures visit Aspergillus Medium.
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