MacConkey Agar
MacConkey Agar – Selective Bacterial Culture Medium
Selective and Differential Medium for Isolation of Gram-Negative Enteric Bacteria
Product Identification
Catalog Number: AS-1282
Format: Dehydrated culture medium
Pack Sizes: 100 g, 500 g, bulk supply available
Product Overview
MacConkey Agar is a selective and differential culture medium designed for the isolation of Gram-negative enteric bacteria and the differentiation of organisms based on lactose fermentation. It is widely used in microbiological laboratories for water, food, environmental, pharmaceutical, and research applications.
The medium contains selective agents that suppress the growth of Gram-positive bacteria, while lactose and a pH indicator enable visual differentiation between lactose-fermenting and non-lactose-fermenting organisms. Lactose fermenters typically produce pink to red colonies, whereas non-fermenters form colourless or translucent colonies.
Ausamics MacConkey Agar is manufactured to deliver consistent selectivity, clear colony differentiation, and reproducible performance across routine microbiological testing.
Key Features & Benefits
Selective for Gram-negative bacteria via bile salts and crystal violet
Differential based on lactose fermentation and pH change
Clear visual distinction between fermenting and non-fermenting organisms
Suitable for routine isolation and enumeration workflows
Consistent batch-to-batch quality
Typical Applications
Microbiology & Research Laboratories
Isolation and differentiation of enteric Gram-negative bacteria
Presumptive differentiation of lactose-fermenting organisms such as Escherichia coli
Detection of non-lactose-fermenting organisms including Salmonella spp.
Food, Water & Environmental Testing
Assessment of Gram-negative bacterial contamination
Hygiene monitoring and quality control testing
Environmental and surface microbiology studies
Pharmaceutical & Industrial Microbiology
Environmental monitoring programmes
Microbial quality control testing
Principle of the Medium
MacConkey Agar contains bile salts and crystal violet, which inhibit Gram-positive organisms and allow selective growth of Gram-negative bacteria. Lactose serves as a fermentable carbohydrate, and neutral red functions as a pH indicator.
Acid production from lactose fermentation lowers the pH, causing colonies to appear pink to red. Non-lactose-fermenting organisms do not acidify the medium and therefore produce colourless or pale colonies.
Typical Composition
Peptone and proteose peptone – nutrient sources
Lactose – fermentable carbohydrate
Bile salts and crystal violet – selective agents
Neutral red – pH indicator
Sodium chloride – osmotic balance
Agar – solidifying agent
(Exact formulation details are provided in the Certificate of Analysis.)
Physical Properties
Appearance (dehydrated): Pinkish-red powder
Appearance (prepared): Pink to light red agar
Final pH (prepared medium): 7.1 ± 0.2 at 25 °C
Preparation (Summary)
Suspend the required quantity of dehydrated medium in purified water, heat with agitation until fully dissolved, sterilise by appropriate laboratory methods, and dispense into sterile containers or plates.
(Refer to internal laboratory protocols for detailed preparation procedures.)
Storage & Stability
Dehydrated medium: Store at 15–30 °C in a dry, sealed container
Prepared medium: Store at 2–8 °C
Protect from moisture and direct light
Intended Use
For laboratory research and microbiological testing use only.
Not for human or veterinary diagnosis, therapeutic use, or consumption.
Quality & Supply Assurance
Manufactured under controlled conditions
Performance tested for selectivity and differentiation
Consistent batch-to-batch quality
Supplied by Ausamics Life Science
Customs & Trade Information
HS / AHECC Code: 3821.00.00
Prepared culture media for development or maintenance of microorganisms