Characterization of Actinomyces

 

Introduction:

·   The Actinomycetes are aerobic, filamentous bacteria that form branching mycelia superficially similar to those of the Fungi but they are prokaryotes whereas fungi are eukaryotes, so the mycelia formed by the former are appreciably smaller.

·   The best known Actinomycetes genus is Streptomyces, which contains some 500 species, all with a characteristically high GC content (69–73 per cent).

·    Indeed, the characteristic musty (earthy) smell of many soils is due to the production of a volatile organic compound called Geosmin. A high proportion of therapeutically useful antibiotics derive from Streptomyces species, including well-known examples such as streptomycin, erythromycin and tetracycline

·     Most Actinomycetes, including Streptomyces, are aerobic; however, members of the genus Antinomies are facultative anaerobes.

For isolation of soil Actinomycetes, following points are important.

·     Pretreatment of soil sample: Mix the soil sample with CaCo3, chitin and incubate for  few days and centrifuge soil sample for 20 min at 1500 RPM & use supernatant

·     Select correct selective media :Glucose Asparagine agar (GAA) medium

·     Use antifungal agent : Cyclohexamidin, nystatin  etc.

·     Incubate plate at 25-28° C

Requirements:

soil sample, Sterile distilled water, Glucose asparagine

·     Glucose                                                      10.0 gm.

·     Asparagine(Add After Autoclave)  0.5 gm.

·     Yeast extract                                            0.5 gm.

·     K2HPO4                                                      0.5 gm.

·     MgSO4.7H2O                                           0.25 gm.

·     Agar                                                             30.0 gm.

·     D/w                                                             1000 ml

·     pH                                                               7.2 ± 0.2                                          

Procedure:

1.      Add approximately 1 gm. pretreated soil sample in 10 ml sterile distilled water under aseptic conditions.

2.      Mix well and allow soil particles to settle down.

3.     With help of a sterile pipette add 0.2 ml of soil supernatant on to sterile GAA plate. Spread it uniformly on the surface of medium with glass spreader.

4.     Incubate plates at room temperature for 2-4 days.

5.     After incubation observe plates for the growth of Actinomycetes, & study their characteristics.

6.     With the help of needle pick up some colony & tease the structure well perform gram staining

7.     Streak the GAA slant from the culture suspension and incubate at room temperature for 2-4 days.