Peptone Water is recommended by BIS (1) for detection of Indole production by Escherichia coli. A slightly different formulation of Peptone water/ Peptone water with phenol red is recommended (2,3,4) for studying the ability of organisms to ferment a specific carbohydrate which aids in differentiation of genera and species. Peptone water with phenol red is recently recommended by ISO committee (5) to study fermentation reactions of Yersinia entrocolitica . Peptone water with pH adjusted to 8.4 is suitable for the cultivation and enrichment of Vibrio species.
Peptic digest of animal tissue provides essential nutrients. Sodium chloride maintains the osmotic balance. To detect indole production add 0.5 ml of Kovacs reagent to the tube and shake the tube gently. Appearance of a red colour indicates presence of indole.
Storage and Shelf-life:
Store below 30°C in tightly closed container and the prepared medium at 2 - 8°C. Use before expiry date on the label.
References:
1. Bureau of Indian Standards IS: 5887 (Part I) 1976, reaffirmed 1986.
2. Macfaddin J., 1980, Biochemical Tests for Identification of Medical Bacteria, 2nd ed., Williams and Wilkins, Baltimore.
3. Finegold and Baron, 1986, Bailey and Scotts Diagnostic Microbiology, 7th ed., The C.V Mosby Co., St. Louis.
4. Lennette and others (Eds), 1985, Manual of Clinical Microbiology, 4th ed. ASM, Washington D.C.
5. International Organization for Standardization (ISO), 1994, Draft ISO/ DIS 10273.