Used in microbiology to detect motility, hydrogen sulfide production, and indole formation in bacterial isolates, particularly for differentiating members of the Enterobacteriaceae family. This semi-solid medium allows simultaneous assessment of three key biochemical traits. Bacterial motility is observed by diffuse growth spreading from the inoculation line. Hydrogen sulfide production is indicated by the formation of black precipitate (iron sulfide) when H₂S reacts with iron salts in the medium. Indole production is detected by adding Kovac’s reagent after incubation, resulting in a red ring if indole is present. This makes the medium efficient for preliminary identification and classification of gram-negative rods.