MacConkey Agar is a selective and differential medium used for the isolation of gram-negative enteric bacteria. It is used to distinguish lactose-fermenting gram-negative bacteria from lactose non-fermenting gram-negative bacteria. It is also used to isolate coliforms and intestinal pathogens.
Composition of MacConkey Agar
The MacConkey Agar is composed of a mixture of peptones, lactose, and bile salts, which helps to create an environment selective for the growth of certain gram-negative bacteria. The addition of bile salts and crystal violet to the agar inhibits the growth of gram-positive bacteria. The media also contains the sugar lactose, with the presence of Neutral red indicator, helps to distinguish between lactose-fermenting and non-fermenting bacteria.
When bacteria are inoculated onto the MacConkey Agar, the lactose-fermenting bacteria will produce acid and gas and form visible colonies with a pink or red colour. On the other hand, the lactose non-fermenting bacteria will not produce acid or gas and form colourless colonies. This difference in colour is due to the presence of the neutral red pH indicator which changes colour in the presence of acids.
In addition to the colour difference, the presence of certain enzymes can also be used to differentiate between the two types of bacteria. Bacteria that are able to ferment lactose will produce a number of enzymes, such as β-galactosidase and β-glucuronidase, that are responsible for the breakdown of lactose into its component sugars. On the other hand, bacteria that are unable to ferment lactose will not produce these enzymes and will not be able to break down the lactose.
In conclusion, the MacConkey Agar is a valuable tool for distinguishing lactose-fermenting bacteria from lactose non-fermenting bacteria. The presence of certain enzymes and the colour difference between the two types of bacteria can be used to determine which type of bacteria is present.
TM Media Manufacturer of Culture Media
TM Media has been catering to the microbial needs of industries for 31 years. They have over 2,000 Dehydrated Culture Media.
At TM Media, 25+ variants of MacConkey Agar are available for extensive identification and characterization of microorganisms.
TM Media’s MacConkey Agar collection includes M-MacConkey Broth, MacConkey Agar (W/ CV, NaCl, 0.15% Bile Salta, & 1% Lactose), MacConkey Agar (W/ 0.15% Bile Salts, CV, & NaCl) (Veg.), MacConkey Agar W/O CV, NaCl, W/ 0.5% Sodium Taurocholate, and many more.
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