What are the two types of coliform testing?

The two primary methods used for coliform testing are the Membrane Filter Technique and Multiple Tube Fermentation.

The Membrane Filter Technique involves passing a water sample through a membrane filter that traps bacteria present in the water. Following this, the filter is placed on a selective growth medium and incubated. This allows for the enumeration of coliform colonies by counting the number of typical colonies formed, which can indicate the level of coliform contamination in the water.

On the other hand, Multiple Tube Fermentation is a statistical method that involves several tubes of broth being inoculated with different dilutions of the water sample. After incubation, the presence of gas or acid indicates coliform growth, and the results are interpreted using the Most Probable Number (MPN) estimation. This method is beneficial for estimating coliform counts in water samples where the concentration may be quite low.

These methods are crucial for assessing water quality and ensuring it meets safety standards, as coliform bacteria are indicators of fecal contamination and overall water safety.