Description

Pre-enrich food samples prior to the isolation of Salmonella species using Thermo Scientific™ Oxoid™ Buffered Peptone Water (Dehydrated). Buffered Peptone Water is a non-selective pre-enrichment medium. It also provides conditions for resuscitation of cells that have been injured by processes of food preservation.

Low numbers and/or sub-lethally injured Salmonella spp. cells may be present in a test food sample. Pre-enrichment in non-selective Buffered Peptone Water allows the cells time to repair and multiply before being introduced into a selective culture, improving the chances of recovering Salmonella species from the sample.

• Supports high growth and recovery rate: rich in nutrients, the medium produces high resuscitation rates and supports intense growth.
• Helps recovery of sub-lethally damaged salmonellae: the phosphate buffer system of the medium prevents bacterial damage due to changes in pH of the medium and helps the recovery of sub-lethally damaged salmonellae that may be sensitive to low pH.

It was noted by Edel and Kampelmacher¹ that sub-lethal injury to salmonellae may occur in many food processes. In a survey involving isolation of salmonellae from meat that had been artificially contaminated with sub-lethally injured organisms, pre-enrichment in buffered peptone water at 37°C for 18 hours before selection in Brilliant Green Tetrathionate Bile Broth showed superior results compared with a direct selection method.

Sadovski² reported that, in experiments involving isolation of salmonellae from frozen vegetables, the rapid drop in pH when using lactose broth³ as a pre-enrichment medium was detrimental to the recovery of salmonellae. This was due to the enhanced sensitivity to low pH of freeze-injured salmonellae which may contaminate frozen vegetables. Pre-enrichment with Buffered Peptone Water maintained a high pH over a period of 24 hours of incubation. The vegetable tissue has a low buffering capacity and the medium overcame this problem.

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Remel™ and Oxoid™ products are now part of the Thermo Scientific brand