Which statement correctly describes the action of bacteriocins in Gram-positive bacteria?

Which statement correctly describes the action of bacteriocins in Gram-positive bacteria?

• A. Form pores in the cell membrane
• B. Inhibit DNA replication
• C. Inhibit RNA polymerase only
• D. Inhibit protein synthesis only

Answer: (A)

Bacteriocins produced by Gram-positive bacteria mainly kill neighboring cells by forming pores in the cytoplasmic membrane. This pore-forming action disrupts the membrane’s integrity, allowing ions and small metabolites to leak out and collapsing the proton motive force, which quickly halts energy production and leads to cell death. Many Gram-positive bacteriocins, such as lantibiotics like nisin, insert into the membrane and create these pores; some also bind lipid II to localize their action and can interfere with cell wall synthesis, but the lethal effect centers on membrane disruption. Mechanisms like inhibiting DNA replication, RNA polymerase, or protein synthesis are typical of other antibiotics, not the defining action of these bacteriocins in Gram-positive species. So, the statement that best describes their action is pore formation in the cell membrane.

Bacteriocins produced by Gram-positive bacteria mainly kill neighboring cells by forming pores in the cytoplasmic membrane. This pore-forming action disrupts the membrane’s integrity, allowing ions and small metabolites to leak out and collapsing the proton motive force, which quickly halts energy production and leads to cell death. Many Gram-positive bacteriocins, such as lantibiotics like nisin, insert into the membrane and create these pores; some also bind lipid II to localize their action and can interfere with cell wall synthesis, but the lethal effect centers on membrane disruption. Mechanisms like inhibiting DNA replication, RNA polymerase, or protein synthesis are typical of other antibiotics, not the defining action of these bacteriocins in Gram-positive species. So, the statement that best describes their action is pore formation in the cell membrane.