Final answer:
InlA and InlB are required for the invasion of host cells by the bacterium Listeria monocytogenes. They facilitate bacterial uptake into host cells, which is crucial for infection. Biofilm formation is an adaptive strategy that provides bacteria with increased resistance to antibiotics and protection from the host immune response.
Step-by-step explanation:
InlA and InlB are both surface proteins of the bacterium Listeria monocytogenes, which are required for b) invasion of host cells. These proteins facilitate the bacteria's penetration into non-phagocytic cells, thereby contributing to the pathogen's ability to cause infection. InlA and InlB bind to host cell receptors and induce phagocytosis-like cellular uptake, which is critical for the bacterium's life cycle within host organisms. Biofilm formation confers numerous advantages to bacteria, such as antibiotic resistance, protection against the host immune system, and enhanced survival in harsh environments. Biofilms form when bacteria adhere to surfaces and produce an extracellular polymeric matrix, which can hinder antibiotic penetration, protect against phagocytosis, and facilitate cell-cell communication through quorum sensing. This matrix makes biofilm-associated bacteria significantly more resistant to antibiotics than planktonic (free-floating) bacteria.