Why should young bacterial culture be used for motility test?

Young bacterial cultures are used for the motility test because the bacterial cells are more motile and have greater motility. As bacterial cultures age, the cells become less motile and may lose their ability to move. To ensure accurate results in detecting bacterial motility, it is essential to use a young culture that is actively growing and motile. Using an old culture can result in false-negative results, where motile bacteria may appear non-motile due to reduced motility or loss of flagella. Therefore, it is crucial to use a fresh, young culture to obtain reliable results in motility testing.