Used primarily in microbiological testing to detect and enumerate coliform bacteria and Escherichia coli in water, food, and pharmaceutical samples. It supports the growth of gram-negative bacteria while inhibiting gram-positive organisms due to bile salts. The double concentration enhances the detection of low-level contaminants by providing a richer nutrient environment. Often employed in most probable number (MPN) tests, it allows for the presumptive identification of fecal contamination through gas and acid production from lactose fermentation. Its formulation is especially useful in environmental monitoring and quality control where high sensitivity is required.