11th Class Biology Biological Classification And System Of Classification / जैविक वर्गीकरण और वर्गीकरण की प्रणाली Actinomycetes

It is a group of unicellular branched filamentous bacteria which resemble fungal mycelia. They grow in the form of radiating colonies in cultures and therefore, commonly called ray fungi. They are Gram +ve chemo-organotrophic, saprotrophic bacteria. Most species are facultative anaerobic. These are generally present as decomposers in soil. The filaments are aseptate (non-septate) branched and very thin (about 0.2 to 1.2 mm in width). The wall contains mycolic acid. They reproduce asexually by means of conidia, which are produced at tips of filaments. The endospores are not formed. Most of these secrete chemical substances having antimicrobial activities called antibiotics. Some of the most common and effective antibiotics are obtained from the different species of the genus streptomyces.

Some species are pathogenic and cause diseases in plant, animal and human beings, e.g., Mycobacterium. Some common diseases in plants are yellow ear rot of wheat (Tundu disease) caused by Corynebacterium tritici and scab of potato by Streptomyces scabies.