Dehydrated culture media
Sellers Agar
Differential medium for studies of Gram-negative, non-fermenting bacteria.
- Cat. No.
- LC-1065
- Category
- Dehydrated culture media
- Format
- 500 g
- Storage
- 2 to 25 °C
- Minimum guaranteed shelf life
- 15 months
Sellers Agar is a very useful medium to identify and differentiate Gram-negative, non-fermenting bacilli, such as Pseudomonas aeruginosa and Alcaligenes faecalis. The differentiation is based on the detection of fluorescence, glucose oxidation, production of nitrogen gas and pH changes, from clinical samples and other materials.
Key features
Applications
Detection and differentiation of non-fermentative Gram-negative bacteria.
Industry
Food, water.
Preparation
43.4 g in one liter of distilled water; boil for one minute, dispense into tubes and sterilize in autoclave at 121 °C for 10 minutes.
Principles and uses
Gelatin peptone provides nitrogen, vitamins, minerals and amino acids essential for growth. Yeast extract is a source of vitamins, particularly of the B-group. Magnesium sulfate is a cofactor for various metabolic reactions. Sodium nitrite provides nitrogen to some organisms. L-Arginine provides amino acids for growth. Sodium chloride maintains the osmotic balance. Dipotassium phosphate acts as a buffer system. D-Mannitol fermentation is detected by bromothymol blue as a yellow halo around the colonies. Phenol red is a pH indicator. Bacteriological agar is the solidifying agent.
Acinetobacter calcoaceticus morphologically resemble Neisseria and are frequently erroneously reported as causes of gonococcal urethritis and meningococcal meningitis (resistant to penicillin). To aid in the identification of the non-fermenters, other media such as OF Basal Medium (LC-1500), Indole Nitrate Medium (LC-1504), etc., should be used.
Under UV light only the Pseudomonas exhibit fluorescence, which is stimulated by magnesium and mannitol in the medium. At times, it is necessary to hold the tubes for 2 days for Pseudomonas to produce a typical alkaline (blue color) reaction in the medium. After incubation, check for glucose oxidation by the appearance of a yellow band, which can disappear after 24 hours.
Technical specifications
| Solubility | Without residues |
|---|---|
| Appearance | Fine powder |
| Color of the dehydrated medium | Beige |
| Color of the prepared medium | Green |
| Final pH (25 °C) | 6.7 ± 0.2 |
| Amount per litre | 43.4 g |
| Storage | 2 to 25 °C |
Formula
| Ingredient | g/L |
|---|---|
| Bromthymol blue | 0.04 |
| Bacteriological agar | 13.5 |
| Dipotassium phosphate | 1 |
| D-mannitol | 2 |
| Gelatin peptone | 20 |
| L-Arginine | 1 |
| Magnesium sulfate | 1.5 |
| Phenol red | 0.008 |
| Sodium chloride | 2 |
| Yeast extract | 1 |
| Sodium nitrate | 1 |
| Sodium nitrite | 0.35 |
Typical formula in g/L, adjusted and/or supplemented as required to meet performance criteria.
Preparation and use
Preparation
Suspend 43.4 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. Dispense into tubes and sterilize in autoclave at 121 °C for 10 minutes. Allow to cool in a slanted position in order to obtain butts of 3.5 cm depth and a slant length of 7-7.5 cm.
Important: immediately before inoculation, add 0.15 mL or 2 drops of 50% dextrose aqueous solution, allowing it to run down the side of the tube opposite to the slant.
Instructions for use
Inoculate the medium by stabbing the base of the tube with a needle and streaking the slant. Incubate at 35 ± 2 °C for 18-24 hours.
Quality control
Microbiological test
Incubation conditions: 35 ± 2 °C / 18-24 h.
| Microorganism | Specification | Characteristic reaction |
|---|---|---|
| Acinetobacter calcoaceticusATCC 19638 | Good growth | Blue slant, green butt, yellow strip, fluorescence (-) |
| Pseudomonas aeruginosaATCC 27853 | Good growth | Blue-green slant, blue-green butt, blue strip, fluorescence (+), gas/nitrogen (+) |
| Alcaligenes faecalisATCC 8750 | Good growth | Blue-green slant, blue-green butt, fluorescence (-), gas/nitrogen (+) |
Bibliography
- Sellers. J. Bact. 87: 46. 1964.
- Lennette E.H., Spaulding H.E. and Truant P.J. Manual of Clinical Microbiology, 2nd Ed. 1974.
What you receive
The product
Shipped under controlled temperature when the product requires it.
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