MacCONKEY BROTH W/ NEUTRAL RED (as per BIS)

MacConkey Broth Neutral Red is a differential medium used for detection and enumeration of coliforms from a variety of foodstuffs, water samples & clinical specimens. The medium differentiates the organisms on the basis of lactose fermentation which is indicated by a colour change. This medium is recommended by the BIS committee under the specifications IS:5887(Part I and Part II) -1976. The medium contains a Peptic digest of animal tissue which provides the nitrogenous and other essential growth compounds. Sodium chloride maintains the osmotic balance of the cells. The selective action of these media is attributed to the presence of bile salts, which are inhibitory to most species of gram-positive bacteria. Gram-negative bacteria usually grow well on these media and are differentiated by their ability to ferment lactose. The colour change of the medium shown by lactose fermenters is due to production of acid from lactose and a subsequent colour change of the indicator dye when the pH of the media falls below 6.8 as observed by Macconkey Broth Neutral Red. The medium turns pink in case of lactose fermenters and yellow in case of non-lactose fermenters, due to neutral red. Organisms producing gas can be observed in preparation with Durham tubes.

for selective enrichment and enumeration of coliforms.