Palcam Broth
Palcam Broth is a liquid medium used for the selective enrichment of Listeria spp. from food and environmental samples. Casein Peptone and Yeast Extract provide essential nutrients like amino acids, peptides, carbohydrates, vitamins and electrolytes. Esculin and Mannitol are the main source of energy for bacterial growth. Mannitol-fermenting species of Listeria give the broth a yellow color due to the presence of the pH indicator Phenol Red. Lithium Chloride provides selectivity to Palcam Broth due to the high salt tolerance of Listeria spp. Most Gram-negative and Gram-positive bacteria are suppressed by the addition of Polymixin B, Acriflavin, and Ceftazimide to the cooled medium. All members of the Listeria group can hydrolyze Esculin to 6,7-dihydroxycoumarine, which reacts with Ferric Ammonium Citrate and results in the blackening of the medium.