Specifications
Ingredients: gms/lit.Peptone (meat or casein) 1.00Sodium chloride 4.30Disodium hydrogen phosphate dihydrate 7.23Potassium dihydrogen phosphate 3.60Final pH (at 25°C) : 7.0 + 0.2 Directions :Suspend 14.64 grams (the equivalent weight of dehydrated medium per litre) in 1000 ml purified /distilled water. Heat if necessary, to dissolve the medium completely. For preparation of nonfatty products insoluble in water, add 0.1 % w/v Polysorbate 80 to assist the suspension of poorly wettable substances. Dispense in tubes or flasks or as desired and sterilize by autoclaving at 15 lbs pressure 121°C for 15 minutes or as per validated cycle.Principle :Buffered Peptone Water is a pre-enrichment medium designed to help recovery of sub-lethally damaged Salmonellae before transfer to a selective medium. This pre-enrichment medium is free from inhibitors and is well buffered and provides conditions for resuscitation of the cells that have been injured by processes of food preservation. Pre-enrichment in Buffered Peptone Water at 37°C for 18 hours before selection in Tetrathionate Brilliant Green Bile Broth showed superior results compared with direct selection method. The composition of Buffered Peptone Water with NaCl medium is as per IP and EP specifications recommended to dilute the sample for microbial examination. Depending on the amount of fat in the sample to examine the kind and quantity of emulsifying agent to be used. These pre-enrichment media contain peptone as a source of carbon, nitrogen, vitamins and minerals. Sodium chloride maintains the osmotic balance and phosphates buffer the medium. The broth is rich in nutrients and produces high resuscitation rates for sub-lethally injured bacteria and supports intense growth. The phosphate buffer system prevents bacterial damage due to changes in the pH of the medium.