Why is it important to vortex, or mix, thoroughly between each dilution step?

It is important to vortex, or mix, thoroughly between each dilution step because unlike solutions that stay uniformly mixed overtime, suspended materials travel down to the bottom of the containers. For example, a dense bacterial suspension that is left undisturbed will typically form a visible white pellet at the bottom of the tube. The concentration of the bacteria at the tube’s bottom will be higher than at the top. The most effective way to re-suspended bacteria is by using a vortexer. The mixing step is also crucial for the homogeneity of the sample, preventing an uneven distribution of microorganisms. It is also important to thoroughly vortex after each dilution to maintain accuracy in subsequent dilutions, helping to achieve the intended dilution factor.