EPA SM 9223 Enzyme Substrate Coliform Test  


The enzyme substrate test utilizes hydrolyzable substrates for the simultaneous detection of total coliform bacteria and Escherichia coli enzymes. When the enzyme technique is used, the total coliform group is defined as all bacteria possessing the enzyme -D-galactosidase, which cleaves the chromogenic substrate, resulting in release of the chromogen. Escherichia coli are defined as bacteria giving a positive total coliform response and possessing the enzyme -glucuronidase, which cleaves a fluorogenic substrate, resulting in the release of the fluorogen. The test can be used in a multiple-tube, multi-well, or a presenceabsence (single 100-mL sample) format.