(AB) MacConkey Agar, 500 grams

MacConkey Agar is a selective agar medium used for the isolation, differentiation enumeration of the Enterobacteriaceae and other Gram negative bacteria in water, dairy products, other sanitary materials and clinical specimens. Inhibition of Gram positive bacteria is obtained by the bile salts mixture and crystal violet. Lactose fermenting bacteria appear as reddish-pink colonies and non-lactose fermenting bacteria appear as colorless or transparent colonies. Agar medium used for the isolation and differentiation of the Enterobacteriaceae based upon the fermentation of lactose. (Alpha Biosciences # M13-106-500gm)

Use: Agar medium used for the isolation and differentiation of the Enterobacteriaceae based upon the fermentation of lactose.

Description: MacConkey Agar is a selective agar medium used for the isolation, differentiation enumeration of the Enterobacteriaceae and other Gram negative bacteria in water, dairy products, other sanitary materials and clinical specimens. Inhibition of Gram positive bacteria is obtained by the bile salts mixture and crystal violet. Lactose fermenting bacteria appear as reddish-pink colonies and non-lactose fermenting bacteria appear as colorless or transparent colonies.

Formula* per Liter:

• Pancreatic Digest of Gelatin......... 17.0g
• Lactose ..........................................10.0g
• Casein Digest Peptone................... 1.5g
• Bile Salts Mixture ........................... 1.5g
• Peptic Digest of Animal Tissue ...... 1.5g
• Sodium Chloride............................. 5.0g
• Neutral Red .................................... 0.03g
• Crystal Violet .............................. 0.001g
• Agar .................................................13.5g

Final pH: 7.1 ± 0.2 at 25.0°C

* Grams per liter may be adj. or formula supplemented to obtain desired performance

Preparation: Mix 50 grams of the medium in one Liter of purified water until evenly dispersed. Heat with repeated stirring and boil for one minute to dissolve completely. Distribute and autoclave at 121.0°C for 15 minutes.

Quality Control Specifications:

1. The powder is homogeneous, free flowing and light pinkish-beige.
2. Visually the prepared medium is clear to slightly hazy and medium to dark pinkish purple.
3. Expected cultural response after 18-24 hours at 35.0°C.

Organism                                                                                    Result

Escherichia coli ATCC 25922                                   Growth, Red-purple colonies

Proteus mirabilis ATCC 12453                             Growth, Clear, Swarming Inhibited

Salmonella typhimurium ATCC 14028                          Growth, Clear colonies

Enterococcus faecalis ATCC 29212                                  Growth Inhibited

Storage: Store the sealed bottle containing the dehydrated medium at 2 to 30.0°C. Once opened and recapped, place the container in a low humidity environment at the same storage temperature. Protect it from moisture and light. The dehydrated medium should be discarded if it is not free flowing or if the color has changed from the original light pinkish-beige color.