Fungi are eukaryotic organisms whose cells have a distinct nucleus that contains the cell's genetic material and is surrounded by a special envelope called the nuclear membrane. Fungi may be unicellular or multicellular. Large multicellular fungi such as mushrooms, may look some what like plants, nut they cannot carry out photosynthesis as they lack necessary photosynthesis machinery. True fungi have cell walls composed primarily of a substance called chitin. The unicellular form of fungi, yeasts are oval shaped microorganisms larger than bacteria.
a. Yeast : Saccharomyces cerevisiae
Size : Range 5.0 - 10.0 μm
Characteristics :
* Yeasts are eukaryotic, unicellular organisms.
* They grow on laboratory cultivation media.
* They reproduce by asexual cell division, budding and by asexual processes.
Practical significance :
* Yeasts are used in production of alcoholic beverages eg. Saccharomyces cerevisiae.
* They are also used as food supplement ( Single cell protein -- Candida utilis ).
* They also cause disease eg. Candidiosis by Candida albicans.
b. Molds :
The most typical fungi are molds. Molds form mycelia, which are long filamentous that branch and interwind. The cottony growth sometimes found on bread and fruit are mold mycelia. Fungi can reproduce sexually or asexually. They obtain nourishment by absorbing solutions of organic material from their environment.
Size : Range 2.0 -- 10.0 μm by several mm.
Characteristics :
* Molds are eukaryotic, multicellular with many distinctive structural features.
* They are cultivated in laboratory media.
* They are devoid of chlorophyll.
* True fungi are composed of filaments and masses of cells which make up the body of the organism known as a mycelium.
* The reproduce by fission, by budding or by means of spores borne on fruiting structures that are quite distinctive for certain species ( sexual and asexual processes ).
Practical Significance :
* Molds are responsible for decomposition ( deterioration ) of many material, eg. Aspergillus niger in the deterioration of wood or cellulosic material.
* They are useful for industrial production of many chemicals including ( Penicilium chrysogenium )
* They cause diseases to human beings, other animals and plants.
Dictostelium ( slime mold ), Rhizidiomyces, Muzor, Neurospora, Alternaria are the representative examples of fungi.