Used primarily in microbiology for the enumeration and detection of coliform bacteria and other gram-negative enteric bacteria in food, water, dairy, and environmental samples. The medium contains bile salts and crystal violet to suppress the growth of gram-positive bacteria and some normal flora, allowing selective growth of target gram-negative organisms. Lactose fermenters, such as Escherichia coli, produce acid that lowers the pH, appearing as red colonies due to the neutral red indicator. Non-fermenters, including pathogens like Salmonella and Shigella, appear as colorless or pale colonies, aiding in preliminary differentiation. Commonly used in quality control laboratories for assessing microbial contamination and ensuring compliance with safety standards.