Which type of stain would most likely be used to visualize the structure of a bacterial capsule?

Using a negative stain is the most effective method for visualizing the structure of a bacterial capsule. This technique involves adding a dye that does not penetrate the bacterial cells but instead stains the background, allowing the clear, halo-like appearance of the capsule to stand out against the stained background.

Negative staining is particularly useful for capsules, which can be difficult to visualize with other staining techniques since capsules can be washed away or become distorted with heat fixation. The negative stain preserves the natural structure of the capsule, providing a clearer image for observation under a microscope.

In contrast, simple stains color the entire bacterial cell uniformly, making it hard to differentiate the capsule from the cell itself. Differential stains highlight differences between bacterial types or structures but may not clearly delineate the capsule. The Gram stain, while valuable for classifying bacteria based on cell wall composition, does not effectively highlight capsule structures. Thus, negative staining is the preferred method for observing and studying bacterial capsules in microbiology.