Brilliant Green Bile Media

Abstract

An attempt is made to determine the optimum concentration of bile and brilliant green in brilliant green lactose peptone bile medium, for use in the presumptive test in the bacteriological examination of water. Comparisons, showing the effect of bile and brilliant green upon the development of the colon organism, were made by making actual bacterial counts after a definite short incubation period. The results indicate that the original medium described by Muer and Harris, (5% dried bile, 1% peptone, 1% lactose, and 1:10,000 billiant green) when adjusted to pH = 7.1, did not show an appreciable inhibition of the colon organism. It is further shown that a medium containing 2% bile, 1% peptone, 1% lactose and 1:75,000 brilliant green supports a more rapid development of the colon organism at pH = 6.9 than does the original brilliant green bile medium at its optimum pH.