Purple HiVeg™ Agar Base

Principle and Interpretation

These media are prepared by replacing Special peptone and Beef extract with HiVeg special peptone and HiVeg extract which are free from BSE/TSE risks. Purple HiVeg Media are the modification of Purple Media which were originally formulated by Vera (1). HiVeg extract and HiVeg special peptone supply the essential nutrients especially nitrogenous to the growing organisms. Sodium chloride maintains the osmotic balance of the medium. Bromo cresol purple is the pH indicator which turns yellow at acidic pH. Gas production is evident by its collection in Durham's tube. The acid produced during the fermentation of carbohydrate causes bromo cresol purple, the pH indicator to turn yellow. Purple HiVeg Broth is inoculated with 18 to 24 hours old pure culture and incubated for 24 to 72 hours (upto 30 days if necessary) at 35 ± 2°C either in an aerobic or anaerobic atmosphere depending on the organism being tested. It is recommended (3) to add carbohydrate in 1% concentration to avoid possible reversion reactions except glucose (dextrose). If the medium containing carbohydrate is sterilized by autoclaving, precautions should be taken to use minimum amount of heat required for sterilization to avoid hydrolysis of the carbohydrate.