2.1 Inhibitors of cell wall synthesis

As you saw in Activity 2, the cell wall is essential for normal functioning of the bacterial cell. Antibiotic inhibitors of cell wall synthesis block the production of peptidoglycan , the main component of the cell wall. Cross-linking between peptidoglycan chains forms a strong, mesh-like structure that gives the cell wall structure and rigidity, and protects the underlying cell membrane from osmotic damage when water moving into the cell by osmosis could cause it to burst, or lyse. Disruption of the peptidoglycan layer of the cell wall can therefore result in cell lysis (Figure 3).

Examples of cell wall synthesis inhibitors are the ß-lactam antibiotics. These include penicillin and its derivatives, and the cephalosporins. All ß-lactam antibiotics contain a core chemical structure called a ß-lactam ring (Figure 4) which determines the mode of action of this class of antibiotics.

The ß-lactam antibiotics interfere with the formation of the peptidoglycan cross-links, thereby weakening the cell wall. You will learn more about the precise mechanism in this week’s case study (Section 3). For now, you can see the effect of the disrupted cell wall on bacterial growth in Video 3.