TERGITOL-7 AGAR BASE, MODIFIED

Tergitol-7 Agar is a selective and differential medium for the detection and enumeration of coliforms in water. Chapman modified his original formula of Tergitol-7 Agar by addition of Triphenyl Tetrazolium Chloride (TTC). It is now recommended by ISO Committee. Tergitol-7 is a selective agent which inhibits gram positive organisms and minimises swarming of Proteus species enabling better coliform recovery. Lactose fermentation is observed by change in colour of bromo thymol blue, the pH indicator. Triphenyl Tetrazolium Chloride (TTC) allows earlier recognition and identification of Escherichia coli and Enterobacter aerogenes in water and food.
Filter the specimen to be analyzed through two membranes. Place the membrane upon two TTC Tergitol Agar plates. Incubate one plate at 37?C for 24 hours (total coliforms) and the other at 44?C for 18-24 hours (faecal coliforms). The yellow colonies with deep yellow halo after incubation at 44?C should be identified as faecal coliform bacteria.

for selective isolation and identi?cation of coliform bacteria from water