ACTINOMYCETES
(Actino means - Ray; Mycetes means - Fungi), Coined By : Harz in 1877
DEFINITION:
Actinomycetes are unicellular, aerobic and gram-positive bacteria that forms branching hyphae . They normally undergo fragmentation and produce asexual spores. They closely resemble fungi in overall morphology. Most of the actinomycetes are non-motile when motility is present is confined to flagellated spores.
GENERAL CHARACTERISTICS:
* Actinomycetes species are primarily soil inhabitant and widely distributed . Additional they are also a marine habitat . Therefore they are also known as a "Treasure house of the secondary metabolites .
* Actinomycetes form colonies that are leathery and many produce pigments and are responsible for the geosmin ( earthy) odor .
* The second edition of Bergey's Manual classifies the actinomycetes and other high G + C gram positive bacteria using 16SrRNA data .
ADVANTAGES:
* They play an vital role in degrading an enormous number and variety of organic compounds and are extremely important in the mineralization of organic matter .
* The aerobic gram-positive actinomycetes belonging to the genus Frankia are bacteria that grows in symbiotic association with the roots of higher non leguminous plants and fixes atmospheric nitrogen .
* They are producers of the most of the antibiotics such as amphotericin, nystatin, chloramphenicol, gentamycin, erythromycin, vancomycin, tetracycline, novobiocin, neomycin, etc.
* Actinomycetes plays an extremely important in the treatment of cancer, as well as variety of applications in bioremediation .
DISADVANTAGES:
* Actinomyces are responsible for actinomycoses, ocular infections, and periodontal disease in human. The most important pathogen is A.israelii
* C.diphtheria is the causative agent of diphtheria in human
* N.asteriodes is a species of nocardia that cause nocardiosis ,a severe pulmonary infection in human and other animals .
LIFE CYCLE OF ACTINOMYCETES:
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