Macconkey Agar 500g

A modification of the original medium with the exception of crystal violet, selective and differential medium for cultivation of enteric microorganisms from a variety of clinical specimens. Recommended for use in microbiological examination of foodstuffs and for direct plating / inoculation of water samples for coliform counts . These media are also accepted by the Standard Methods for the Examination of Milk and Dairy Products. HiMedia M008 refers to MacConkey Agar, a selective & differential microbiological medium used to isolate and differentiate lactose fermenting (pink/red colonies) from non-lactose fermenting (colorless) Gram-negative enteric bacteria, crucial for identifying pathogens like E. coli, Salmonella, and Shigella from clinical samples, appearing as a light yellow to pink powder that forms a red/orange gel, inhibiting Gram-positive growth via bile salts and crystal violet. Key Features & Use

• Type: Selective & Differential Agar.
• Purpose: Isolates Gram-negative bacteria; differentiates lactose fermenters (pink/red) from non-fermenters (colorless).
• Components: Contains peptone, bile salts, lactose, neutral red (pH indicator), and agar. Crystal violet (CV) may be included or excluded depending on the specific variant (e.g., M008 vs. M081).
• Mechanism: Bile salts and crystal violet inhibit Gram-positive bacteria; lactose & neutral red differentiate based on fermentation, turning colonies pink/red when acid is produced.
• Appearance: Light yellow to pink powder; forms a red/orange gel when prepared.
• Applications: Culturing enteric bacteria from clinical samples, food, and water. 

Examples of Cultural Response (with CV)

• E. coli, Klebsiella: Pink to red colonies with bile precipitate (lactose fermenters).
• Salmonella, Shigella: Colorless, transparent colonies (non-lactose fermenters).
• Staphylococcus aureus: Inhibited (Gram-positive).