Neutralizing Buffered Peptone Water

Cat. no. K281 Neutralizing Buffered Peptone Water (nBPW), 20x125mm Tube, 10mL 20 tubes/box
Cat. no. U181 Neutralizing Buffered Peptone Water (nBPW), 500ml Wide Mouth Polycarbonate Bottle, 400mL 10 bottles/box
Cat. no. U183 Neutralizing Buffered Peptone Water (nBPW), 2oz. Polypropylene Bottle, 25mL 25 bottles/box


Hardy Diagnostics Neutralizing Buffered Peptone Water (nBPW) is recommended for use in the recovery of sub-lethally injured Salmonella species from industrial samples prior to selective enrichment and isolation.

This product is not intended to be used for the diagnosis of human disease.


Salmonella spp. may be present in foods, particularly poultry products, yet cells may be sub-lethally injured by food processing techniques. Consequently, it may be difficult to recover injured cells of this organism using selective media and the organism may go undetected using traditional culture techniques. Beginning July 1, 2016, the United States Department of Agriculture, Food Safety and Inspection Service (USDA FSIS) instituted new guidelines for the development of Neutralizing Buffered Peptone Water (nBPW) to aid in the recovery of Salmonella spp. from domestic and imported poultry verification sampling, including chicken carcass rinses, poultry parts rinses and young turkey carcass sponge swabs.(6) The USDA FSIS also states nBPW is safe as a direct rinse or swab, and should be used as a non-selective pre-enrichment medium to promote the recovery of sub-lethally injured bacteria, particularly Salmonella spp.(6)

nBPW contains peptones that act as nitrogenous compounds to promote bacterial growth. Phosphate salts in the buffer help to maintain pH. Maintenance of pH is important when attempting to recover sub-lethally injured cells, because a low pH can be detrimental to the repair and growth of damaged microorganisms. In addition, nBPW contains neutralizing agents to reduce the inhibitory effects of carryover from microbial interventions.(6)


Ingredients per liter of deionized water:*

Buffered Peptone Water (BPW) 20.0g
Sodium Bicarbonate 12.5g
Lecithin 7.0g
Sodium Thiosulfate 1.0g

Final pH 7.7 +/- 0.5 at 25ºC.

* Adjusted and/or supplemented as required to meet performance criteria.


Storage: Upon receipt, store away from direct light at 2-8ºC. away from direct light. Media should not be used if there are any signs of deterioration, discoloration, contamination, or if the expiration date has passed. Product is light and temperature sensitive; protect from light, excessive heat, moisture, and freezing.



Sample Collection: Consult reference methods for complete procedures on sample collection.(1-6)

Method of Use: Gently mix nBPW prior to use. Consult listed references for complete procedures for handling poultry carcasses prior to rinsing and swabbing and for information on the recovery of Salmonella spp. from food or poultry samples.(1,2,5,6)

1. Inoculate 10g or 10mL of sample for every 50mL of Neutralizing Buffered Peptone Water (nBPW).

2. Incubate at 35ºC. for 18 to 24 hours.

3. Transfer 10mL of the incubated sample to 100mL of Tetrathionate Broth (Cat. no. U165) and incubate at 35ºC. Other selective enrichments may be used.(1,2,5,6)

4. After 24 and 48 hours, subculture to Brilliant Green Agar (Cat. no. G75), XLD Agar (Cat. no. G65) and/or HE Agar (Cat. no. G63) and incubate plates for 18 to 24 hours at 35ºC. NOTE: It is recommended that more than one selective agar be used in parallel, since no single medium is appropriate in all situations, to ensure recovery when salmonellae are present.(1,2,5,6)

5. Examine plates for typical colonies of Salmonella spp. and perform further testing for complete identification.


Consult listed references for appropriate interpretation of results.(1-6)

Following incubation, examine solid media for growth and typical colony morphology.


nBPW is a non-selective medium. Overgrowth of competing flora in the test sample may affect recovery of salmonellae.


Standard microbiological supplies and equipment such as loops, other culture media such as Brilliant Green Agar (Cat. no. G75), XLD Agar (Cat. no. G65), HE Agar (Cat. no. G63), or Tetrathionate Broth (Cat. no. U165), swabs, applicator sticks, incinerators, and incubators, etc., as well as serological and biochemical reagents, are not provided.


Test Organisms Inoculation Method* Incubation Results
Time Temperature Atmosphere
Salmonella enterica
ATCC® 14028
A 18-24hr 35°C Aerobic Growth and typical colony morphology upon subculture to XLD Agar
Escherichia coli
ATCC® 25922
A 18-24hr 35°C Aerobic Partial to complete inhibition upon subculture to XLD Agar



Neutralizing Buffered Peptone Water (nBPW) should appear opaque, cloudy, and light yellow in color.


1. Juven, B.J., N. Cox, J.S. Bailey, J.E. Thomson, O.W. Charles, and J.V. Schutze. 1984. Recovery of Salmonella from artificially contaminated poultry feeds in non-selective and selective broth media. Jour. of Food Prot. ; 47:299-302.

2. Sadovski, A.Y. 1977. J. Food Technology; 12:85-91.

3. American Public Health Association. Standard Methods for the Examination of Dairy Products, APHA, Washington, D.C.

4. APHA Technical Committee on Microbiological Methods for Foods. Compendium of Methods for the Microbiological Examination of Foods, APHA, Washington, D.C.

5. U.S. Food and Drug Administration. Bacteriological Analytical Manual. Arlington, VA

6. USDA FSIS. June 8, 2016. FSIS Notice 41-16. Washington D.C

ATCC is a registered trademark of the American Type Culture Collection.