SDA: Composition, Principle, Preparation, Results, Uses

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Sabouraud Dextrose Agar or SDA was formulaed by Raymond Sabouraud in 1892. Sabouraud Dextrose Agar is used for the cultivation of fungi (yeasts, molds), particularly useful for the fungi associated with skin infections. This medium is also employed to determine microbial contamination in food, cosmetics, and clinical specimens. The pH is adjusted to approximately 5.6 in order to enhance the growth of fungi, especially dermatophytes, and to slightly inhibit bacterial growth in clinical specimens. Antibacterial agents can also be added to augment the antibacterial effect. Chloramphenicol, gentamicin, and tetracycline are selective agents added to inhibit the bacterial overgrowth of competing microorganisms while permitting the successful isolation of fungi and yeasts.

Principle of Sabouraud Dextrose Agar (SDA)

Sabouraud Dextrose Agar contains digests of animal tissues (peptones) which provide a nutritious source of amino acids and nitrogenous compounds for the growth of fungi and yeasts. Dextrose is added as the energy and carbon source. Agar is the solidifying agent. Chloramphenicol and/or tetracycline may be added as broad-spectrum antimicrobials to inhibit the growth of a wide range of gram-positive and gram-negative bacteria. Gentamicin is added to further inhibit the growth of gram-negative bacteria. The pH is adjusted to approximately 5.6 in order to enhance the growth of fungi, especially dermatophytes, and to slightly inhibit bacterial growth in clinical specimens. High dextrose concentration and low pH favor fungal growth and inhibit contaminating bacteria from test samples.

Composition of Sabouraud Dextrose Agar (SDA)

Ingredients Gms/Liter
Dextrose40.0
Peptone10.0
Agar15.0

Final pH ( at 25°C) 5.6±0.2

Preparation of Sabouraud Dextrose Agar (SDA)

  1. Suspend 65 g of the medium in one liter of distilled water.
  2. Heat with frequent agitation and boil for one minute to completely dissolve the medium.
  3. Autoclave at 121° C for 15 minutes.
  4. Cool to 45 to 50°C and pour into petri dishes or tubes for slants.

Result Interpretation on Sabouraud Dextrose Agar (SDA)

Sabouraud Dextrose Agar (SDA)
Fungi Colony morphology
Candida albicans Pasty opaque slightly domed, smooth, and cream or white colonies 
Aspergillus flavusYellow-green powdery on front and pale yellowish on reverse
Aspergillus nigerThe initial growth is white, becoming black later on giving a “salt and pepper appearance” which results from darkly pigmented conidia borne in large numbers on conidiophores and reverse turning pale yellow
Aspergillus fumigatusBluish-green powdery colonies on front and pale yellow on the reverse.
Trichosporon mucoidesWhite to cream, yellowish, wrinkled
Geotrichum candidumWhite to cream-colored, flat with aerial mycelium

Uses of SDA

  1. SDA is primarily used for the selective cultivation of yeasts, molds and aciduric bacteria.
  2. The medium is often used with antibiotics for the isolation of pathogenic fungi from material containing large numbers of other fungi or bacteria.
  3. This medium is also employed to determine microbial contamination in food, cosmetics, and clinical specimens.

Limitations of SDA

  1. Some strains may be encountered that grow poorly or fail to grow on this medium.
  2. Antimicrobial agents added into a medium to inhibit bacteria may also inhibit certain pathogenic fungi.
  3. Avoid overheating a medium with an acidic pH, this may result in a soft medium.
  4. For identification, organisms must be in pure culture.
  5. Morphological, biochemical, and/or serological tests should be performed for final identification.
  6. It does not promote the conidiation of filamentous fungi.

About Author

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Sagar Aryal, PhD

Dr. Sagar Aryal is a microbiologist, researcher, and science communicator from Nepal. He is also co-founder and Research Head of the Department of Natural Products at the Kathmandu Research Institute for Biological Sciences (KRIBS), where he leads research on natural product discovery and microbial biodiversity. Dr. Aryal earned his Ph.D. in Microbiology from Tribhuvan University, Kathmandu, Nepal, in 2025, supported by a DAAD Research Grant and a University Grants Commission (UGC) Nepal Ph.D. Fellowship. His research interests include Actinomycetes, Myxobacteria, microbial taxonomy, and natural products, particularly the discovery of bioactive compounds with potential pharmaceutical applications. He isolated and identified Nocardia nepalensis, a novel bacterial species from Nepal, contributing to understanding microbial diversity in the region. Dr. Aryal has published more than 16 research articles in international journals and contributed three book chapters to established academic publications. He has presented scientific research findings and developed international research collaborations through visits to more than 18 countries across Asia, Europe, North America, and Oceania. From 2023 to 2025, he served as the American Society for Microbiology (ASM) Young Ambassador to Nepal. Since December 2025, he has served as an Editorial Board Member of Scientific Reports, a Nature Portfolio journal. In recognition of his scientific contributions, Dr. Aryal received the NAST Science and Technology Youth Award 2025 from the Nepal Academy of Science and Technology. He previously received the Frs. Locke and Stiller Research Award (LSRA) for the 2017-2018 cycle from St. Xavier's College, Kathmandu, and a Nepal Academy of Science and Technology (NAST) Research Grant for 2017-2018. Alongside his scientific career, Dr. Aryal has more than 15 years of experience in blogging, content writing, and search engine optimization (SEO).

7 thoughts on “SDA: Composition, Principle, Preparation, Results, Uses”

  1. When did these symptoms of this fungus first appear, or when did this type of fungus first appear, and what factor encouraged its increased spread?

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  3. The amount of the inhibitory agents ( chloramphenicol and tetracycline) and at what stage of preparation is added in the SDA

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