Dehydrated culture media
MacConkey Agar w/o Crystal Violet and w/o Sodium Chloride
Differential medium for the detection and isolation of enterobacteria, and inhibition of Proteus swarming. Recommended for urine analysis.
- Cat. No.
- LC-1098
- Category
- Dehydrated culture media
- Format
- 500 g
- Storage
- 2 to 25 °C
- Minimum guaranteed shelf life
- 15 months
MacConkey Agar w/o Crystal Violet & w/o NaCl is a differential medium used for the detection and isolation of enteric microorganisms. The lack of sodium chloride provides an electrolyte deficient medium preventing Proteus spp. from spreading (swarming), aiding the detection and isolation of enteric microorganisms. Also, as this medium does not contain crystal violet, staphylococci, enterococci and Mycobacteria species are able to grow well.
Key features
Applications
Differentiation of enterobacteria.
Preparation
47 g in one liter of distilled water; boil for one minute, sterilize in autoclave at 121 °C for 15 minutes.
Principles and uses
Gelatin peptone and peptone mixture provide nitrogen, vitamins, minerals and amino acids essential for growth. Lactose is the fermentable carbohydrate providing carbon and energy. Bile salts are the selective agents and inhibit Gram-positive organisms. Neutral red is the pH indicator. When lactose is fermented, the pH of the medium decreases, changing the color of neutral red into pink. Bacteriological agar is the solidifying agent.
Technical specifications
| Solubility | Without residues |
|---|---|
| Appearance | Fine powder |
| Color of the dehydrated medium | Beige-pink |
| Color of the prepared medium | Red |
| Final pH (25 °C) | 7.4 ± 0.2 |
| Amount per litre | 47 g |
| Storage | 2 to 25 °C |
Formula
| Ingredient | g/L |
|---|---|
| Bacteriological agar | 12 |
| Bile salts No. 3 | 5 |
| Gelatin peptone | 17 |
| Lactose | 10 |
| Neutral red | 0.075 |
| Peptone mixture | 3 |
Typical formula in g/L, adjusted and/or supplemented as required to meet performance criteria.
Preparation and use
Preparation
Suspend 47 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 45-50 °C, mix well and dispense into plates.
Instructions for use
Inoculate and 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 |
|---|---|---|
| Klebsiella aerogenesATCC 13048 | Good growth | Pink colony |
| Proteus vulgarisATCC 13315 | Good growth | Inhibited swarming. Colorless colony |
| Enterococcus faecalisATCC 19433 | Good growth | Pink point colony |
| Escherichia coliATCC 25922 | Good growth | Red-pink colony |
| Staphylococcus aureusATCC 25923 | Good growth | Pale pink colony |
Bibliography
- MacConkey, A. 1905. Lactose-fermenting bacteria in feces. J. Hyg 5:333-379.
- Murray, P.R., E.J. Baron, M.A. Pfaller, F.C. Tenover, and R.H. Yolken (eds) Manual of clinical microbiology, 6th ed. American Society for Microbiology, Washington, D.C.
- Mazura-Reets, G.T. Neblett, and J.M. Galperin, 1979. MacConkey Agar: CO2 vs. ambient incubation. Abst. Ann. Mtg. American Society for Microbiology. C179.
What you receive
The product
Shipped under controlled temperature when the product requires it.
Lot certificate
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