Which of the following statements best describes why Staphylococcus aureus needs iron?

• A. Iron is necessary for S. aureus to replicate its DNA directly.
• B. Iron is essential for S. aureus because it acts as a cofactor in enzymes involved in cellular respiration.
• C. Iron is used by S. aureus to synthesize its capsule polysaccharides.
• D. Iron is required by S. aureus to maintain its cell wall structure.

Answer: (B)

Verified step by step guidance

1. Understand the biological role of iron in bacterial cells, particularly in Staphylococcus aureus. Iron is a critical micronutrient that many bacteria require for various metabolic processes.
2. Recall that iron commonly functions as a cofactor for enzymes, especially those involved in electron transport and cellular respiration, which are essential for energy production in bacteria.
3. Evaluate each statement by considering the known functions of iron: DNA replication requires nucleotides and enzymes but iron is not directly involved in replicating DNA; capsule polysaccharide synthesis and cell wall maintenance do not primarily depend on iron.
4. Focus on the statement that iron acts as a cofactor in enzymes involved in cellular respiration, as this aligns with the well-established role of iron in bacterial metabolism and energy generation.
5. Conclude that the best description of why Staphylococcus aureus needs iron is because it is essential for enzymatic functions in cellular respiration, supporting the bacterium's energy needs and survival.