Tergitol 7 Agar

Tergitol 7 Agar is a solid medium for the selective isolation of?Escherichia?coli?and other coliform bacteria. Enzymatic Digests of Casein and Animal Tissue are the nitrogen and mineral sources, while Yeast Extract supplies B-complex vitamins. Lactose is the fermentable carbohydrate, whose utilization is indicated by a color change of the pH indicator Bromthymol Blue from blue to yellow. Tergitol 7 is a selective agent inhibiting the growth of Gram-positive microorganisms, spore-forming Gram-negative bacteria, and swarming of?Proteus?spp. Agar is the gelifying agent. When TTC is added to the medium, it serves as an indicator of bacterial growth. This compound is rapidly reduced to insoluble red formazan by most organisms. Lactose-fermenting organisms continue to provide yellow to greenish-yellow colonies, while non-lactose fermenters appear red due to uptake and reduction of the TTC.