Buffered Peptone Water | DM494

Buffered Peptone Water | DM494

A pre-enrichment medium designed to increase the recovery of sub-lethally injured Salmonella spp. prior to selective enrichment and isolation.

MAST Buffered Peptone Water (DM494) is intended to be used as a pre-enrichment medium, prior to selective enrichment, in the isolation of Salmonella spp. from food. It is particularly valuable for the resuscitation of cells injured during food preservation processes. This was confirmed by Sadovski who recommended Buffered Peptone Water as a preenrichment medium for use with frozen vegetable samples, to overcome problems encountered through the increased acid sensitivity of freeze injured salmonellae and to counteract the low buffering capacity of vegetable tissue. After pre-enrichment, samples are transferred to enrichment broth for further incubation. Pietzsch recommended Tetrathionate broth but later work by Vassiliadis found RappaportVassiliadis Broth (DM269) superior for the isolation of Salmonella spp. from both food and environmental samples.

2. Technical Formula*

3. Directions
1. Suspend by swirling 39.0g of powder in 1 litre or the contents of the sachet in the stated volume of distilled water.
2. Autoclave at 121ºC (15p.s.i.) for 15 minutes.
3. Cool to 50ºC and add 5-7% sterile defibrinated horse blood where required.

4. In Use
Columbia Agar can be used alone, or with the addition of 5-7% blood. The medium can be made selective with the addition of
various antibiotics