Brilliant Green Bile HiCynth™ Broth, 2%

Principle And Interpretation

Brilliant Green Bile Broth 2% is one of the most widely used medium for the detection of coliform bacteria in water, wastewater, foods, and milk and dairy products. This medium is formulated as per APHA (1, 2, 3) for the presumptive identification and confirmation of coliform bacteria (4, 5). This medium is also recommended by the ISO Committee for enumeration of coliforms by most probable number technique (6). Brilliant Green Bile HiCynth™ Broth 2% is the modification of the same using chemically defined peptone free from animal and vegetable peptones to avoid BSE/TSE risks associated with animal peptones.

HiCynth™ Peptone No.3 serves as a source of essential carbon and nitrogen nutrients, long chain amino acids, vitamins and other growth factors. Lactose is the fermentable carbohydrate. Synthetic detergent inhibits gram-positive bacteria whereas the gram-negative bacteria are inhibited by brilliant green. Production of gas from lactose fermentation is detected by incorporating inverted Durham's tube, which indicates the positive evidence of faecal coliform since non faecal coliforms growing in this medium do not produce gas. Further gas production in EC broth at 45°C used as a confirmation of faecal coliform. Gram-positive spore formers may produce gas if the bile or brilliant green inhibition is weakened by reaction with food material.

During examination of water samples, growth from presumptive positive tubes showing gas in Lactose Broth or Lauryl Tryptose Broth is inoculated in Brilliant Green Bile Broth 2%. Gas formation within 48 ± 2 hours confirms the presumptive test (1).