Used as a substrate in enzymatic assays to detect β-glucuronidase activity, often in molecular biology and microbiology research. It is particularly useful in identifying bacterial colonies, such as E. coli, through the hydrolysis of the compound, which produces an insoluble blue-green indigo dye. This makes it a valuable tool in water quality testing, clinical diagnostics, and genetic engineering for marker gene studies. Its application extends to histochemistry for visualizing enzyme activity in tissue samples.