Sodium Chloride Buffered Peptone Solution EP

This solution is a non-inhibitory medium, therefore allowing an easy recovery of stressed microorganisms. It is rich in nutrients and produces high recovery of damaged cells and intensifies the growth of microorganisms. A feature common to all selective media is that sublethally injured organisms are not generally detected and therefore a recovery step must be included in examination procedures.

Changes in pH may damage bacterial growth. Sodium Chloride Buffered Peptone Solution maintains a high pH via the phosphate buffer system and allows the repair of injured cells which are sensitive to low pH. Meat peptone provides nitrogen, vitamins, minerals and amino acids essential for growth. Sodium chloride supplies essential electrolytes for transport and osmotic balance.

Preparation

Suspend 16.10 grams of the medium in one liter of distilled water. Mix well and dissolve by heating with frequent agitation. Boil for one minute until complete dissolution. Distribute into appropriate containers and sterilize at 121 °C for 15 minutes.

According to the European Pharmacopoeia

According to the European Pharmacopoeia for the examination of TAMC and TYMC in products:

Membrane filtration:

1. Prepare the product sample by suspending, dissolving or diluting the product to be examined in the Sodium Chloride Buffered Peptone Solution.
2. Transfer the appropriate amount of the sample to a membrane filter.
3. Place the membrane on the surface of Trypticasein Soy Agar (LC-1068) in case of TAMC or Sabouraud Dextrose Agar (LC-1024) in case of TYMC.
4. Incubate the plate of Trypticasein Soy Agar (LC-1068) at 30-35 °C for 3-5 days and the plate of Sabouraud Dextrose Agar (LC-1024) at 20-25 °C for 5-7 days.

Plate-count methods:

1. Prepare the product sample by suspending, dissolving or diluting the product to be examined in the Sodium Chloride Buffered Peptone Solution.
2. Inoculate the plates of Trypticasein Soy Agar (LC-1068) in case of TAMC or Sabouraud Dextrose Agar (LC-1024) in case of TYMC, conforming to the pour-plate method or the surface-spread method.
3. Incubate the plates of Trypticasein Soy Agar (LC-1068) at 30-35 °C for 3-5 days and the plates of Sabouraud Dextrose Agar (LC-1024) at 20-25 °C for 5-7 days.
4. Select the plates corresponding to a given dilution and showing the highest number of colonies less than 250 (TAMC) or 50 (TYMC).

Most-probable-number method (only for TAMC):

1. Prepare and dilute the product sample to be examined in Sodium Chloride Buffered Peptone Solution, and inoculate into tubes of Trypticasein Soy Broth (LC-1224).
2. Incubate all tubes at 30-35 °C for 3-5 days.
3. Record for each level of dilution the number of tubes showing growth and determine the most probable number of microorganisms.

• European Pharmacopoeia 9.0