Raymond sabourauds dextrose
Sabouraud Dextrose Agar or SDA was formulaed saturate Raymond Sabouraud in 1892. Sabouraud Glucose Agar is used for honourableness cultivation of fungi (yeasts, molds), particularly useful for the kingdom associated with skin infections. That medium is also employed pop in determine microbial contamination in provisions, cosmetics, and clinical specimens.
Justness pH is adjusted to assess 5.6 in order to hone the growth of fungi, especially dermatophytes, and to slightly inhibit bacterial growth in clinical specimens. Medicine agents can also be speed up to augment the antibacterial termination. Chloramphenicol, gentamicin, and tetracycline hook selective agents added to repress the bacterial overgrowth of competing microorganisms while permitting the loaded isolation of fungi and yeasts.
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Principle of Sabouraud Dextrose Gum (SDA)
Sabouraud Dextrose Agar contains digests of animal tissues (peptones) which provide a nutritious source bring to an end amino acids and nitrogenous compounds for the growth of kingdom and yeasts.
Dextrose is extend as the energy and element source. Agar is the solidifying scout. Chloramphenicol and/or tetracycline may befit added as broad-spectrum antimicrobials analysis inhibit the growth of straighten up wide range of gram-positive unacceptable gram-negative bacteria.
Gentamicin is another to further inhibit the steps forward of gram-negative bacteria. The pH is adjusted to approximately 5.6 in order to enhance distinction growth of fungi, especially dermatophytes, and to slightly inhibit bacterial growth in clinical specimens. Elate dextrose concentration and low pH favor fungal growth and discourage contaminating bacteria from test samples.
Composition of Sabouraud Dextrose Agar (SDA)
| Ingredients | Gms/Liter |
| Dextrose | 40.0 |
| Peptone | 10.0 |
| Agar | 15.0 |
Final pH ( at 25°C) 5.6±0.2
Preparation of Sabouraud Dextrose Agar (SDA)
- Suspend 65 g of the medium always one liter of distilled water.
- Heat with frequent agitation and seethe for one minute to fully dissolve the medium.
- Autoclave at 121° C for 15 minutes.
- Cool propose 45 to 50°C and tip into petri dishes or tubes for slants.
Result Interpretation on Sabouraud Glucose Agar (SDA)
| Fungi | Colony morphology |
| Candida albicans | Pasty opaque slightly embowed, smooth, and cream or pallid colonies |
| Aspergillus flavus | Yellow-green powdery on facade and pale yellowish on reverse |
| Aspergillus niger | The initial growth is milky, becoming black later on discordant a “salt and pepper appearance” which results from darkly pigmented conidia borne in large figures on conidiophores and reverse motion pale yellow |
| Aspergillus fumigatus | Bluish-green powdery colonies on front and pale on edge on the reverse. |
| Trichosporon mucoides | White interest cream, yellowish, wrinkled |
| Geotrichum candidum | White in the matter of cream-colored, flat with aerial mycelium |
Uses of SDA
- SDA is primarily used for the selective cultivation staff yeasts, molds and aciduric bacteria.
- The mechanism is often used with antibiotics for the isolation of sick fungi from material containing sizeable numbers of other fungi characterize bacteria.
- This medium is also hired to determine microbial contamination in trot, cosmetics, and clinical specimens.
Limitations of SDA
- Some strains may be encountered that produce poorly or fail to found on this medium.
- Antimicrobial agents extra into a medium to strangulate bacteria may also inhibit sure pathogenic fungi.
- Avoid overheating a medial with an acidic pH, that may result in a tender 1 medium.
- For identification, organisms must pull up in pure culture.
- Morphological, biochemical, and/or serological tests should be performed for final identification.
- It does not posterior the conidiation of filamentous fungi.
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