What color indicates a negative result in the enzymatic hydrolysis Tween 80 test?

In the Tween 80 test, a negative result is indicated by an amber color. This test is designed to assess the ability of certain microorganisms to hydrolyze Tween 80, a nonionic surfactant. Hydrolysis of Tween 80 leads to the production of fatty acids, which can change the pH of the medium.

When a microorganism is capable of hydrolyzing Tween 80, it typically leads to an alkaline shift in the medium, often resulting in a color change to green (indicating a positive result). Conversely, if no hydrolysis occurs, the pH does not significantly change, maintaining the amber color, which signifies a negative result. This color change is an important visual indicator of the microbial metabolic activity in the medium.

In summary, the amber color indicates the absence of enzymatic activity toward Tween 80, confirming that the organism being tested does not possess the capability to hydrolyze this substrate.