Total coliform as a group of bacteria which is aerobic and facultative anaerobic, gram-negative, nonspore- foaming, rod shaped bacteria which ferment lactose with gas formation within 48 hours at 35°C. These bacteria are found in the intestines of warm blooded animals and therefore are present in sewage, on and in soils, surface waters and vegetation. The total coliform group has been used for sometime as an "indicator organism". An indicator organism by itself is considered to cause no diseases in man or animals, but its presence usually indicates the presence of pathogenic or disease-causing organisms. By measuring the number of total coliform present in a sample a judgment can be made as to the water's usability for a given purpose. Two general types of analyses are possible to enumerate fecal coliforms: [1] MPN - Most Probable Number [2] Membrane Filter – MF. There are three phases of testing for coliform in water and food.
1. Presumptive Test: This test determines the presumptive coliform count. To determine the gases from lactose fermentation.
2. Confirmatory Test: This test is carried out to confirm the count obtained by presumptive testing. To additionally determine gas and acid production obtained from lactose fermentation.
3. Completed Test: The completed testing may be carried out for the evidence that the coliforms found in food are fecal or non-fecal origin or to prove that E. coli is represented in the confirmed coliform count.