What are toxins produced by bacteria to inhibit the growth of similar or closely related bacterial strains?

• A. Endotoxins
• B. Bacteriocins
• C. Exotoxins
• D. Biofilms

Answer: (B)

The main idea being tested is bacterial weapons against closely related strains. Bacteriocins are antimicrobial peptides produced by bacteria to inhibit or kill nearby, related strains, helping the producer secure its niche. These compounds are usually ribosomally synthesized and often accompanied by immunity proteins to shield the producer. They work through mechanisms like pore formation in target cell membranes or degradation of nucleic acids, giving a competitive advantage in dense or stressed environments. This is different from endotoxins, which are components of the Gram-negative outer membrane released upon lysis and primarily affect host organisms; exotoxins, secreted toxins that damage host cells; and biofilms, which are communities that increase survival but are not toxins directed at competing bacteria.