Dehydrated culture media
HC Agar Base
Used with Tween 80 (Polysorbate 80) for the enumeration of molds in cosmetics.
- Cat. No.
- LC-2001
- Category
- Dehydrated culture media
- Format
- 500 g
- Storage
- 2 to 25 °C
- Minimum guaranteed shelf life
- 15 months
HC Agar Base, used with Tween 80 (Polysorbate 80), is used for the enumeration of molds in cosmetics. This medium was described by Mead and O'Neill in 1986. The formulation of HC Agar decreased incubation time to 3 days at 27.5 ± 0.5 °C. The formulation of HC Agar Base is supplemented with Tween 80 (Polysorbate 80) to prepare HC Agar.
Key features
Applications
Selective enumeration of yeasts and molds.
Industry
Cosmetics.
Preparation
54.4 g in 1 liter of distilled water with 20 mL of Tween 80; boil for one minute, sterilize in autoclave at 121 °C for 15 minutes.
Principles and uses
Dextrose is the fermentable carbohydrate providing carbon and energy. Yeast extract is a source of vitamins, particularly of the B-group, essential for bacterial growth. Peptones provide nitrogen, vitamins, minerals and amino acids essential for growth. Magnesium sulfate is a magnesium ion required in a big variation of enzymatic reactions, including DNA replication. The phosphates buffer the pH near neutrality. Ammonium chloride provides essential ions. Sodium carbonate inactivates low levels of preservatives that are active at acidic pH. Chloramphenicol inhibits bacteria, including Pseudomonas aeruginosa and Serratia marcescens, potential contaminants of cosmetic products. Tween 80 (Polysorbate 80) is incorporated to neutralize phenols, hexachlorophene and formalin that may be present in residual amounts from products. Agar is the solidifying agent.
Technical specifications
| Solubility | Without residues |
|---|---|
| Appearance | Fine powder |
| Color of the dehydrated medium | Beige |
| Color of the prepared medium | Amber, slightly opalescent |
| Final pH (25 °C) | 7.0 ± 0.2 |
| Amount per litre | 54.4 g |
| Storage | 2 to 25 °C |
Formula
| Ingredient | g/L |
|---|---|
| Dextrose | 20 |
| Ammonium chloride | 1.4 |
| Bacteriological agar | 15 |
| Casein peptone | 2.5 |
| Chloramphenicol | 0.1 |
| Disodium phosphate | 3.5 |
| Magnesium sulfate | 0.06 |
| Monopotassium phosphate | 3.4 |
| Peptone | 2.5 |
| Sodium carbonate | 1 |
| Yeast extract | 5 |
Preparation and use
Preparation
Dissolve 54.4 grams of the medium in 1 liter of distilled water and add 20 mL of Tween 80. Mix well and dissolve by heating with frequent agitation. Boil for one minute until complete dissolution. Sterilize in autoclave at 121 °C for 15 minutes. Cool to 50 °C and dispense into appropriate containers.
Instructions for use
Inoculate and incubate at a temperature of 27.5 ± 0.5 °C for 72 hours.
Quality control
Microbiological test
Incubation conditions: 27.5 ± 0.5 °C / 72 h.
| Microorganism | Specification |
|---|---|
| Candida albicansATCC 10231 | Good growth |
| Aspergillus brasiliensisATCC 16404 | Good growth |
| Bacillus subtilisATCC 6633 | Total inhibition |
| Pseudomonas aeruginosaATCC 9027 | Partial inhibition |
Bibliography
- Hitchins, Tran and McCarron. 1995. In FDA bacteriological analytical manual, 8th ed. AOAC International, Gaithersburg, Md.
- Mead and O'Neill. 1986. J. Soc. Cosmet. Chem. 37:49.
- Wolfgang Siegert. Comparison of microbial challenge testing methods for cosmetics. Schülke & Mayr GmbH, Norderstedt, Germany.
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