Which structure is involved in the attachment of bacteria to surfaces?

The structure that is primarily involved in the attachment of bacteria to surfaces is pili. Pili, also known as fimbriae, are hair-like appendages that extend from the surface of many bacteria. They play a critical role in adhesion by allowing bacterial cells to attach firmly to various surfaces, including host tissues or biofilms. This attachment is essential for colonization and can enhance the bacteria's ability to establish infections or thrive in specific environments.

In contrast, flagella primarily facilitate motility, allowing bacteria to move toward nutrients or away from harmful substances. Capsules serve different functions, such as protecting the bacterium from phagocytosis or desiccation, but they are not as specialized for surface attachment as pili. Endospores are highly durable structures that certain bacteria form to survive harsh conditions and do not play a role in attachment to surfaces. The specialization of pili for adhesion makes them crucial for the survival and pathogenicity of many bacterial species.