Nutrient Broth with pH 6.9 and devoid of NaCl is a relatively simple formulation containing beef extract and peptic digest of animal tissue which can support the growth of non-fastidious microorganisms. It has the formula originally developed for use in Standard Methods for the Examination of Water and Waste Water (1). If this medium is incorporated with 6.5% sodium chloride, then it acts as a differential and selective agent by interfering with the osmotic balance and the permeability of membrane of majority of microorganisms. On addition of 6.5% Sodium chloride, the medium can also be used to determine salt tolerance of bile esculin positive Enterococci (2).
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. Clesceri L. S, Greenberg A. E. and Eaton A. D., (Eds.), 1998, Standard Methods for the Examination of Water and Wastewater, 20th Ed., APHA, Washington, D.C.
2. MacFaddin J. F., 1985, Media for Isolation-Cultivation-Identification-Maintenance of Medical Bacteria, Vol. I, Williams and Wilkins, Baltimore.