Potato Dextrose Agar Powder
Potato Dextrose Agar (PDA) Powder
Dehydrated microbiological culture medium for cultivation, enumeration, and maintenance of fungi and yeasts. Manufactured in Australia with full batch documentation.
Overview
Potato Dextrose Agar (PDA) is one of the most widely used fungal culture media in microbiology. Formulated from potato infusion solids and dextrose, its low pH (5.6) selectively favours fungal and yeast growth while suppressing most bacteria. The rich carbon source provided by dextrose and the organic nitrogen from potato extract support vigorous mycelial growth, sporulation, and pigment development across a broad range of species.
AuSaMicS AS-1330 is a ready-to-reconstitute dehydrated powder manufactured to microbiological grade standards, supplied with full batch documentation (COA, TDS, SDS) and dispatched same-week from Melbourne.
Composition (per litre of prepared medium)
| Ingredient | Concentration (g/L) | Function | Mechanism |
|---|---|---|---|
| Potato infusion solids | ~4.0 | Nitrogen & vitamin source | Provides amino acids, vitamins (B-group), and trace minerals derived from potato extract, supporting fungal metabolic pathways and secondary metabolite production |
| Dextrose (D-Glucose) | 20.0 | Primary carbon & energy source | Fermentable sugar metabolised via glycolysis; high concentration (20 g/L) promotes rapid mycelial growth and sporulation; also lowers water activity slightly |
| Agar | 15.0 | Solidifying agent | Polysaccharide gelling agent; forms firm gel at 40–45 °C; not metabolised by most fungi; provides stable surface for colony morphology assessment |
| Final pH: 5.6 ± 0.2 at 25 °C — Acidic pH selectively inhibits most bacteria while permitting unrestricted fungal and yeast growth | |||
Applications
Strengths & Limitations
Comparative Media — Fungal & Yeast Culture
| Medium | pH | Selectivity | Best Use | Antibacterial | AuSaMicS Cat. |
|---|---|---|---|---|---|
| Potato Dextrose Agar (PDA) — AS-1330 | 5.6 | Low (pH-based) | General fungi & yeasts, sporulation, food testing | pH only | AS-1330 |
| Rose Bengal Chloramphenicol Agar | 7.2 | Medium | Yeast & mould enumeration in food (ISO 21527) | Chloramphenicol + Rose Bengal | AS-1347 |
| Sabouraud Dextrose Agar (SDA) | 5.6 | Low (pH-based) | Dermatophytes, clinical fungi, cosmetic QC | pH only | AS-1350 |
| Malt Extract Agar (MEA) | 5.4 | Low | Brewery, fermentation, malt-utilising fungi | pH only | AS-1285 |
| Czapek Dox Agar | 7.3 | Low | Aspergillus, Penicillium species identification | None | AS-1219 |
| DRBC Agar (Dichloran Rose Bengal) | 5.6 | Medium | Foods with high mould counts — colony size restriction | Dichloran + Rose Bengal | AS-1226 |
Cross-Reference / Equivalent Products
AS-1330 is equivalent to the following products from major international suppliers:
| Supplier | Product Name | Catalogue Number |
|---|---|---|
| Oxoid (Thermo Fisher) | Potato Dextrose Agar | CM0139 |
| BD Difco | Potato Dextrose Agar | 213400 |
| Merck (Sigma-Aldrich) | Potato Dextrose Agar | 70139 |
| Thermo Fisher (Oxoid) | Potato Dextrose Agar | CM0139B |
| AuSaMicS | Potato Dextrose Agar Powder | AS-1330 |
Preparation Instructions
2. Mix: Stir to homogenise. Heat gently if required to dissolve completely.
3. Autoclave: Sterilise at 121 °C for 15 minutes (15 psi).
4. Cool: Allow to cool to 47–50 °C before pouring plates.
5. Pour: Dispense approximately 15–20 mL per standard Petri dish. Allow to solidify at room temperature.
Storage of prepared plates: Store inverted at 2–8 °C, protected from light. Use within 4 weeks of preparation.
Note: For food and environmental samples with heavy bacterial contamination, add chloramphenicol (50 mg/L) or Rose Bengal (25 mg/L) aseptically after autoclaving and cooling to 50 °C.
Frequently Asked Questions
Technical Data Sheet — AS-1330 Potato Dextrose Agar
Technical Overview & Biochemistry
Potato Dextrose Agar supports fungal and yeast growth through a combination of a rich nutrient matrix and selective pH. Potato infusion provides water-soluble organic compounds — including reducing sugars, amino acids, and B-group vitamins — extracted from dehydrated potato tissue. The high dextrose concentration (20 g/L) serves as the primary fermentable carbon source, supporting both aerobic and fermentative metabolic pathways. The acidic final pH (5.6 ± 0.2) inhibits bacterial growth via acid stress on bacterial cell membranes while remaining permissive for most fungi, which tolerate a broad pH range (3–8).
Agar at 15 g/L provides a firm, stable solid surface that is not metabolised by fungi, allowing accurate colony morphology assessment, sporulation observation, and colony counting.
Physical & Chemical Properties
| Parameter | Specification |
|---|---|
| Appearance (dehydrated) | Cream-coloured, homogeneous, free-flowing powder |
| Appearance (prepared medium) | Pale yellow, translucent agar — firm gel consistency |
| pH (prepared medium at 25 °C) | 5.6 ± 0.2 |
| Reconstitution rate | 39 g per litre of distilled water |
| Gelling temperature | Solidifies below 45 °C; melts above 80 °C |
| Sterilisation | Autoclave at 121 °C, 15 min (15 psi) |
| Water activity (prepared) | ~0.990–0.993 |
| Moisture content (powder) | ≤6% |
| HS Tariff Code | 3821.00 |
Detailed Composition (per litre)
| Ingredient | g/L | Function | Mechanism |
|---|---|---|---|
| Potato infusion solids | ~4.0 | Nutrient source | Supplies amino acids, B-vitamins, and trace minerals; promotes secondary metabolite and pigment production in moulds |
| Dextrose (D-Glucose) | 20.0 | Carbon & energy source | Primary substrate for fungal glycolysis and the TCA cycle; drives rapid biomass and spore production; catabolite repression regulates secondary metabolism |
| Agar | 15.0 | Solidifying agent | Linear polysaccharide (agarose/agaropectin) forming thermoreversible gel; metabolically inert to most fungi; provides stable surface for colony observation |
Mode of Action — Selectivity
The selective action of PDA relies primarily on its acidic pH (5.6). At this pH, bacterial cell membranes experience proton motive force disruption and inhibition of nutrient transport, effectively suppressing most Gram-positive and Gram-negative bacteria. Fungi and yeasts possess a more robust plasma membrane composition (ergosterol-rich) and active proton-pumping ATPases that maintain cytoplasmic pH homeostasis across a wide extracellular pH range (3–8), allowing unrestricted growth. No antibiotic selectivity is employed in the standard formulation.
Quality Control — Performance Test Organisms
| Organism | ATCC / Reference | Inoculum (CFU) | Incubation | Expected Growth | Result |
|---|---|---|---|---|---|
| Aspergillus brasiliensis | ATCC 16404 | ≤100 CFU | 25 °C, 5 days | Good growth; black conidia | PASS |
| Candida albicans | ATCC 10231 | ≤100 CFU | 25 °C, 3 days | Good growth; cream colonies | PASS |
| Saccharomyces cerevisiae | ATCC 9763 | ≤100 CFU | 25 °C, 3 days | Good growth; white-cream colonies | PASS |
| Escherichia coli (inhibition check) | ATCC 25922 | ≤100 CFU | 35 °C, 48 h | Inhibited / no growth | PASS |
Literature & References
- Atlas, R.M. (2010). Handbook of Microbiological Media, 4th edn. CRC Press, Boca Raton. pp. 1583–1584.
- ISO 21527-1:2008. Microbiology of food and animal feeding stuffs — Horizontal method for the enumeration of yeasts and moulds. International Organization for Standardization.
- APHA (2015). Standard Methods for the Examination of Water and Wastewater, 23rd edn. Method 9610 (Fungi).
- Samson, R.A. et al. (2010). Food and Indoor Fungi. CBS-KNAW Fungal Biodiversity Centre, Utrecht.
- Hocking, A.D. & Pitt, J.I. (1980). Dichloran-glycerol medium for enumeration of xerophilic fungi from low-moisture foods. Applied and Environmental Microbiology, 39(3), 488–492.
Download TDS Document
Safety Data Sheet — AS-1330 Potato Dextrose Agar
Full 16-section Safety Data Sheet compliant with the Globally Harmonised System (GHS) and Australian Work Health and Safety (WHS) Regulations. Download the complete SDS document below before handling this product.
SDS Section Summary
| Section | Heading | Key Information |
|---|---|---|
| 1 | Identification | Potato Dextrose Agar Powder, AS-1330, AuSaMicS Pty Ltd, support@ausamics.com |
| 2 | Hazard identification | Not classified as hazardous under GHS. No signal word. Dust may cause mild irritation. |
| 3 | Composition / information on ingredients | Potato infusion solids, Dextrose, Agar — all non-hazardous biological/food-grade materials |
| 4 | First aid measures | Inhalation: fresh air. Skin/eyes: wash with water. Ingestion: rinse mouth, seek advice if unwell. |
| 5 | Firefighting measures | Not flammable. Use CO₂ or dry powder extinguisher. Wear SCBA in enclosed fire scenarios. |
| 6 | Accidental release | Sweep up powder; avoid generating dust; dispose as general laboratory waste per local regulations. |
| 7 | Handling & storage | Store at 2–25 °C, sealed, dry. Avoid moisture ingress. Keep away from incompatible oxidising agents. |
| 8 | Exposure controls / PPE | Lab coat, nitrile gloves, safety glasses. No respiratory protection required for normal use. |
| 9 | Physical & chemical properties | Cream powder, pH 5.6 (prepared), hygroscopic, not flammable, not explosive |
| 10 | Stability & reactivity | Stable under recommended conditions. Incompatible with strong oxidisers. No hazardous decomposition products under normal use. |
| 11 | Toxicological information | Not classified as acutely toxic. Individual components have low toxicity profiles. Dust may cause mechanical irritation. |
| 12 | Ecological information | Not classified as environmentally hazardous. Biodegradable components. Avoid large releases to waterways. |
| 13 | Disposal considerations | Autoclave prepared media before disposal. Dispose of dry powder as general laboratory waste per local council requirements. |
| 14 | Transport information | Not classified as dangerous goods (UN/ADG). No special transport requirements. |
| 15 | Regulatory information | Not subject to AICIS notification. Complies with Australian WHS model regulations. |
| 16 | Other information | Issued by AuSaMicS Pty Ltd. For laboratory use only. See full SDS for complete details. |
Download Full SDS Document (16-Section, GHS-Compliant)
Certificate of Analysis — AS-1330 Potato Dextrose Agar
A batch-specific Certificate of Analysis is issued for every lot of AS-1330 Potato Dextrose Agar. The COA confirms that the supplied batch has been tested against the specifications below and meets all stated requirements. Retain your COA for laboratory audit and accreditation purposes.
Specification Table
| Test Parameter | Method | Specification | Typical Result | Status |
|---|---|---|---|---|
| Appearance (powder) | Visual | Cream, free-flowing, homogeneous | Cream powder, homogeneous | PASS |
| pH (prepared, 25 °C) | Potentiometry | 5.6 ± 0.2 | 5.6 | PASS |
| Moisture content | Loss on drying | ≤6.0% | 4.2% | PASS |
| Gel strength (prepared) | Visual / rheology | Firm gel, no syneresis | Firm, clear surface | PASS |
| Growth promotion — Aspergillus brasiliensis ATCC 16404 | Pour plate / incubation | Good growth ≥ reference | Good; black conidia | PASS |
| Growth promotion — Candida albicans ATCC 10231 | Pour plate / incubation | Good growth ≥ reference | Good; cream colonies | PASS |
| Growth promotion — Saccharomyces cerevisiae ATCC 9763 | Pour plate / incubation | Good growth ≥ reference | Good; white colonies | PASS |
| Inhibition — Escherichia coli ATCC 25922 | Streak plate / incubation | Inhibited / no growth | No growth | PASS |
| Sterility (prepared medium) | Incubation 35 °C / 48 h | No growth | No growth | PASS |
Download Sample COA