Used as a chromogenic substrate in microbiological assays, particularly in the detection and enumeration of specific bacterial enzymes such as β-glucuronidase or esterases. Upon enzymatic hydrolysis, it releases a colored indoxyl derivative, enabling visual or spectrophotometric detection. Its lipophilic tail enhances cell membrane permeability, making it effective in whole-cell assays. Commonly applied in selective media for pathogenic bacteria like E. coli in water and food testing. Also utilized in histochemistry for enzyme activity localization in tissues.