cholera-red reaction

chol·er·a-·red re·ac·tion

a test for Cholera vibrio whereby the addition of 3-4 drops of sulfuric acid (concentrated, chemically pure) to an 18-hour-old bouillon or peptone culture of the organism produces a rose-pink to claret color.

cholera-red reaction

An obsolete bacteriologic method for detecting indole production by certain bacteria, in particular by Vibrio cholerae, in which a red colour is produced when sulfuric acid is added to the culture medium.

The reaction was supplanted by the indole test, which uses hydrochloric acid.