Escherichia coli ATCC 8739: red colonies,
Salmonella typhimurium ATCC 14028: colourless colonies,
Pseudomonas aeruginosa ATCC 9027: colourless colonies,
Staphylococcus aureus ATCC 6536: no growth.
Escherichia coli ATCC 8739: turbid growth; acid and gas production,
Staphylococcus aureus ATCC®6538: turbid growth; no acid or gas production.
Peptone 20.0 g, Lactose 10.0 g, Bile salts 5.0 g, Sodium chloride 5.0 g, Neutral red
0.075 g, Agar 12.0 g, Distilled water ad 1000ml.
Peptone 20.0 g, Lactose 10.0 g, Bile salts 5.0 g, Sodium chloride 5.0 g,
Bromocresol purple 0.01 g, Distilled water ad 1000ml.
Adjust pH to 7.4 ± 0.2 at 25 ºC. Sterilize by autoclaving at 121 ºC for 15 minutes.
Mac Conkey agar:without salt - recommended for urocultures;
Mac Conkey agar:without crystal violet - less selective medium and allows growing
of some Gram-positive cocci other than enterococci.
Mac Conkey agar:with lactose replaced by sorbitol - used fpr EHEC
(enterohaemorrhagic E. coli) strains isolation which are sorbitol-negative and form
colorless colonies. For medium preparation replace 10g lactose with 10g sorbitol.
Selective medium for the isolation of Salmonella, Shigella and coliform bacteria from faeces, urine, foods, water and pathologic
materials. MacConkey Broth is used as a presumptive medium for the detection of the coliforms from water. MacConkey Agar is
frequently used as selective media for Enterobacteriaceae. The growth of Gram-positive germs is inhibited by the bile salts and the
crystal violet. Lactose-positive germs form red colonies, lactose-negative germs form colorless colonies.
(c) Costin Stoica