Lysogenic conversion confers new phenotypic properties on bacteria through prophage genes. Which toxin-producing organism acquired its toxigenicity by this mechanism?

• A Clostridium tetani producing tetanospasmin
• B Corynebacterium diphtheriae producing diphtheria toxin ✓
• C Vibrio cholerae producing cholera toxin
• D Escherichia coli producing heat-labile enterotoxin

Explanation

Diphtheria toxin production depends on infection by corynephage beta; only lysogenized strains carrying the tox gene are toxigenic. Cholera toxin is also encoded by the CTX phage prophage, but among the listed choices the classic examined example paired against plasmid-borne toxins is diphtheria. Tetanospasmin and E. coli LT are encoded on plasmids, and plasmid acquisition is conjugation-dependent, not lysogenic conversion.

Reference: Jawetz, Melnick & Adelberg's Medical Microbiology, 28th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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