Sorbitol Peptone Broth and Bile Salts (PSB) ISO
Principles and uses
Sorbitol Peptone Broth And Bile Salts (PSB) is a medium recommended by ISO 10273 for the selective enrichment of Yersinia enterocolitica in food samples. Outbreaks of gastroenteritis associated with Yersinia enterocolitica are increasing. Contaminated food products such as pork, beef, and raw and processed milk have been identified as sources of infection.
Enzymatic digest of casein provides nitrogen, vitamins, minerals and amino acids essential for growth. Sodium chloride supplies essential electrolytes for transport and osmotic balance. Potassium phosphates act as a buffer system. Sorbitol is the fermentable carbohydrate providing carbon and energy.
Preparation
Suspend 31 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. Dispense into appropriate containers and sterilize in autoclave at 121°C for 15 minutes.