KF (Kenner Fecal) Streptococcal Broth was developed by Kenner et al. for the detection and enumeration of enterococci in waters. They found that this formulation was superior to other liquid media for the recovery of enterococci in Most Probable Number (MPN) test systems. The medium is not specific for the presumptive identification of group D streptococci. The addition of 1% TTC (2,3,5-Triphenyl Tetrazolium Chloride), in the membrane filter procedure causes the enterococci to have a deep red color as a result of tetrazolium reduction to formazan, an insoluble red pigment, by actively growing microbial cells. Peptone mixture provides nitrogen, vitamins, minerals and amino acids essential for growth. Yeast extract is a source of vitamins, particularly of the B-group. Maltose and Lactose are the fermentable carbohydrates as carbon and energy sources. Sodium glycerophosphate is a buffering agent. Sodium azide is a selective agent that inhibits Gram-negative bacteria. Sodium chloride supplies essential electrolytes for transport and osmotic balance. Bromocresol purple is the pH indicator with a color change from purple to yellow. The presence of intestinal enterococci is an indicator for faecal contamination, especially when the contamination occurred long before, and the less resistant coliform bacteria, including Escherichia coli, are already dead when the analysis is carried out.
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