Actinomycetes

detail information about the actinomycetes

1. ST. PIOUS X DEGREE AND PG COLLOEGE FOR WOMEN M.SC MICROBIOLOGY I SEMESTETR PAPER I- GENERAL MICROBIOLOGY AND MICROBIAL PHYSIOLOGY SEMINAR TOPIC : ACTINOMYCETES BY:- P. DHARANI ROLLNO:- 029

2. Actinomyces means “ ray fungus”. They are unicellular, gram + ve, filamentous, anaerobes or microaerophilic in nature. The fermentative types of actinomycetes are found in body cavities of humans and animals. They can grow on simple lab media but they are slow growing. They are causative agents for few human diseases such as actinomycosis & various abscesses and plant diseases such as potato scab, blueberry etc.

3. CHARECTERISTICS Actinomycetes share the following physicochemical properties : Actinomycetes usually have  1-2 µm  diameter. They generally possess a rod shape with a filamentous or branched structure. The filaments contain  mumaric acid . Most of the species are  aerobic , while a few are anaerobes to facultative aerobes. Cell wall and internal structures are similar to bacteria. The cell wall of actinomycetes consists of  mycolic acid . The growth or reproduction of actinomycetes is slower than the bacteria and fungi. Hence , actinomycetes are sometimes called as “ Slow growers ”. They are having  60-78%  of G+C content. Actinomycetes are most abundant in  soil  (10 6 -10 8 g) and  marine habitat . The majority of species are usually non-motile, non-capsulated and non-acid fast. They show optimum growth at  alkaline pH.

4. They produce filamentous hyphae and there is no endospore Production. These are secondary metabolite producers and the representing genera- S treptomyces, etc. LIFE CYCLE OF ACTINOMYCETES

5. The life cycle of actinomycetes completes in six steps: Germination Vegetative growth Coiling Septation Spore maturation Release of spore CLASSIFICATION Actinomycetes have seven families, based on the hyphal and reproductive structures, they are: Streptomycetaceae: e.g. Streptomyces Nocardiaceae: e.g. Nocardia Micromonosporaceae: e.g. M icromonospora Actinoplanaceae: e.g. Actinoplanes Dermatophilaceae: e.g. Geodermatophilus Frankiaceae: e.g. Frankia Actinomycetaceae: e.g. Actinomyces

6. The disease caused is known as actinomycosis, it is a chronic suppurative and Granulomatous characterized by multiple abscesses, tissue disruption, fibrosis and Formation of sinuses. It is an endogenous infection and more often affects immuno compromised Individuals. Actinomycosis have 4 clinical forms: 1. Cervicofacial : lumpy jaw which effects the cheeks and sub maxillary regions. 2. Thoracic: effects the lungs 3. Abdominal: effects the Illeocaecal region- tissues with low O2 supply 4. Pelvic Smelly pus is discharged from the sinuses in actinomycosis, this pus contains yellow sulphur granules, which gives very bad odor. We collect this discharged pus and use it as a specimen for laboratory diagnosis.

7. STREPTOMYCES They form long, branched aerial mycelia consisting of non-fragmenting filaments. These hyphae are septate & produce spores[conidia] in long spore c hain[straight, curved/ coiled]. CHARACTERISTIC FEATURES: The nature of spore surface which when observed under microscope appear smooth, spiny or hairy. The pigmentation of mycelium may be white, yellow, violet, red, blue, g reen/ grey. The color of pigment exuded by mycelium. Physiological characteristics such as utilization of various carbon source, organic acids, reduction of nitrate & hydrolysis of urea. The conidia of this group are not endospores & not as heat resistant as the endospores of true bacteria. A temp of 65⁰C for 30mins is enough to kill the spores. These colonies are tiny & bright coloured and grow best at 25⁰C at ph 8-9.

8. Most of these species are saprophytes in soil & some are pathogenic to animals and plants. ANTIBIOTICS A large number of species and sub species of this group can produce Antibiotics. E.g.- tetracycline's, Oxytetracycline & erythromycin. St. griseus – streptomycin St. fradiae – neomycin St. aureofaciens - aureofacin ECONOMIC IMPROTANCE

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