Study of water-borne coliform bacteria by use of desoxycholate agar and violet red bile agar.

Abstract

The presumptive test of water-borne coliform bacteria by use of desoxycholate agar and violet red bile agar were reviewed experimentally by the procedures indicated in the Standard Methods of Analysis, authorized by the Pharmaceutical Society of Japan. According to the results obtained on 5 kinds of known strains of coliform bacteria and many samples of sewage and sea water, the authors proposed the criteria for detecting coliform bacteria as shown below ; After incubation at 34-36°C for 18-22h on desoxycholate agar, typical colonies appear as round, rice grain like or oval, more than 1 mm in diameter, presenting the color of 1 R 4/14, vivid purplish red ; 1 R 3/10, deep purplish red ; 4 R 3.5/10, deep red or 6 RP 4/13.5, vivid red purple, comparing with the color-standards specified in Japanese Industrial Standard. After incubation at 34-36°C for 18-22h on violet red bile agar, typical colonies appear as round or oval, more than 1 mm in diameter, presenting the color of 1 RP 4/13, vivid red purple or 7.5 P 2.4/8, deep purple