MacCONKEY AGAR (as per USP/EP/BP/JP)

MacConkey Agar is used for the isolation, enumeration and enrichment of Enterobacteriaceae. The medium is designed to selectively isolate gram-negative and enteric (normally found in the intestinal tract) bacilli and differentiate them based on lactose fermentation. Subsequently, MacConkey Agar is recommended for use in microbiological examination of foodstuffs and for direct plating/inoculation of water samples for coliform counts. This media is also accepted by the standard methods for the examination of milk and dairy products and pharmaceutical preparations.

MacConkey Agar is prepared in accordance with the harmonized method of USP/EP/JP/BP/IP. Pancreatic digestion of gelatin and Proteose peptone supply the necessary nutrients, vitamins and nitrogenous factors required for the growth of microorganisms. Lactose has been used at a concentration of 1% (wt/vol.) to detect acidification against the alkalinization caused by peptone catabolism. Neutral red is added to differential media as a pH indicator, to detect changes in hydrogen ion concentration during the growth of an organism as lactose fermentation occurs. Neutral red will change color as the pH changes. Agar is a solidifying agent. Sodium chloride is added to maintain the osmotic balance in the medium. Bile salt and crystal violet provides selectivity against most species of gram-positive bacteria. Lactose fermenting strains grow as red or pink colonies whereas non lactose fermenters grow as colourless colonies. The medium can be easily melted and dispensed into plates or tubes for routine use in any type of laboratory workflow. Once solidified, the samples can be streaked or spread on the surface under aseptic conditions to get well isolated colonies.

MacConkey Agar is used in clinical, food, water, dairy and pharmaceutical analysis for the isolation of enteric bacteria. It also allows for microbial limit testing in compliance with pharmacopeial recommendations. Proper sample handling and incubation environment also contribute to accuracy of results. The medium provides uniform differentiation, enabling easy differentiation of lactose fermenter and non fermenter for subsequent identification.

for isolation, enumeration and enrichment of Enterobacteriaceae