Dehydrated culture media
Yeast Extract Agar (YEA) ISO
For the enumeration of a wide spectrum of bacteria, yeasts and molds in water.
- Cat. No.
- LC-1049
- Category
- Dehydrated culture media
- Format
- 500 g
- Storage
- 2 to 25 °C
- Minimum guaranteed shelf life
- 15 months
- Standards
- ISO 11133ISO 6222
- Also available
- Ready-to-use medium, 5 formats (LC-941)
Yeast Extract Agar is a medium rich in nutrients that permits the recovery of a wide spectrum of bacteria, yeasts and molds. This medium is recommended by ISO 6222 for the plate count of microorganisms in all types of water, including for human consumption.
Key features
Applications
Non-selective enumeration (general use).
Industry
Water.
Standards
ISO 11133, ISO 6222.
Preparation
24 g in one liter of distilled water; boil for one minute, sterilize in autoclave at 121 °C for 15 minutes.
Principles and uses
Tryptone provides nitrogen, vitamins, minerals and amino acids essential for growth. Yeast extract is the water-soluble portion of hydrolyzed yeast and is a source of vitamins, particularly of the B-group. Bacteriological agar is the solidifying agent.
The norm ISO 6222 recommends this medium for the enumeration of culturable microorganisms in potable water at 36 °C and 22 °C.
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) | 7.2 ± 0.2 |
| Amount per litre | 24 g |
| Storage | 2 to 25 °C |
Formula
| Ingredient | g/L |
|---|---|
| Bacteriological agar | 15 |
| Tryptone | 6 |
| Yeast extract | 3 |
Preparation and use
Preparation
Suspend 24 grams of the medium in one liter of distilled water. 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 45 ± 1 °C, mix well and dispense into plates.
According to ISO 6222
Poured plate method:
- Dispense a sample volume or dilution of no more than 2 mL per plate.
- Add 15-20 mL of YEA medium. Let it solidify.
- Invert the plates and incubate at 36 ± 2 °C for 44 ± 4 hours.
- Count the colonies that are observed in each plate and calculate the estimated number of CFU present per mL of sample.
Quality control
According to ISO 11133
Escherichia coli ATCC 25922 / Bacillus subtilis ATCC 6633.
Incubation conditions: 36 ± 2 °C / 44 ± 4 h.
Inoculation conditions: productivity quantitative (100 ± 20 CFU, min. 50 CFU).
Reference media: media batch Yeast Extract Agar already validated.
Rest of strains
Incubation conditions: 22 ± 2 °C / 68 ± 4 h.
| Microorganism | Specification |
|---|---|
| Candida albicansATCC 10231 | Good growth |
| Aspergillus brasiliensisATCC 16404 | Good growth |
| Escherichia coliATCC 25922 | Good growth (2) > 70% |
| Bacillus subtilisATCC 6633 | Good growth (2) > 70% |
Bibliography
- ISO 6222 Water Quality. Enumeration of culturable micro-organisms - colony count by inoculation in a nutrient agar culture medium.
What you receive
The product
Shipped under controlled temperature when the product requires it.
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Tracked shipment
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Frequently asked questions
Can I ask for formats other than those listed?
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