Tergitol 7 Broth

Tergitol 7 Broth is a liquid medium for the selective isolation of Escherichia coli and other coliform bacteria. Proteose Peptone is the nitrogen and mineral source, 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. When TTC is added to the medium, it serves as an indicator of non-lactose fermenters. This compound is rapidly reduced to insoluble red formazan by most organisms, thus changing the medium color to red.