TRYPTONE SOYA YEAST EXTRACT AGAR

Tryptone Soya Yeast Extract Agar is formulated as per APHA for the isolation and cultivation of L. monocytogenes from foods. ISO Committee has recommended this medium for confirmation of Listeria species and can also be used for the cultivation and maintenance of a wide variety of heterotrophic microorganisms. According to FDAs enrichment procedure for isolation of L. monocytogenes from dairy products, the sample to be tested is inoculated in enrichment broth and incubated at 30?C for 24-48 hours. This culture is streaked on Modified McBride Listeria Agar with cycloheximide or Lithium-Phenylethanol-Moxalactam (LPM) Agar and incubated at 35?C for 48 hours. Presumptive Listeria colonies are selected under 45? transillumination and colonies are further purified on Tryptone Soya Yeast Extract Agar under the light illumination. Listeria colonies are dense white to iridescent white appearing as crushed glass. Other colonies tend to be yellowish or orange

for isolation and cultivation of Listeria from Henry?s light