How many steps are in the multiple-tube fermentation test procedure?

The multiple-tube fermentation test procedure consists of three main steps. This test is commonly used in wastewater treatment to determine the presence of coliform bacteria, which indicates potential contamination and helps assess water quality.

The three steps are:

1. Sample Preparation: Water samples are diluted in serial dilutions, ensuring that the concentration of potential bacteria can be evaluated across multiple tubes.

2. Inoculation: The prepared samples are then inoculated into a series of tubes containing a suitable growth medium, such as lactose broth. This medium promotes the growth of bacteria while also allowing for the production of gas, which is used as an indicator of fermentation.

3. Observation and Interpretation: After a specified incubation period, the tubes are examined for gas production and acid formation. The results are then used to determine the Most Probable Number (MPN) of coliforms in the original sample.

By understanding these three steps, it becomes clear why this answer is accurate. Each step plays a crucial role in identifying and quantifying bacteria, which is essential for determining the safety and quality of water in wastewater management.