Bacterial transformation (uptake of naked DNA from the environment) requires the recipient bacteria to be in a state of 'competence.' The Gram-positive organism classically used to discover transformation (Griffith, 1928) was:
- A Staphylococcus aureus
- B Haemophilus influenzae
- C Streptococcus pneumoniae ✓
- D Neisseria gonorrhoeae
Correct answer: C. Streptococcus pneumoniae
Explanation
Frederick Griffith's 1928 experiment used smooth (encapsulated, virulent) and rough (non-encapsulated, avirulent) strains of Streptococcus pneumoniae in mice. When heat-killed smooth strain material was co-injected with live rough strain bacteria, mice died and live smooth pneumococci were recovered — demonstrating transformation (the 'transforming principle' later identified as DNA by Avery, MacLeod, and McCarty in 1944). Haemophilus influenzae and Neisseria gonorrhoeae are also naturally transformable, but the historical experiment was with S. pneumoniae.
Reference: Ananthanarayan & Paniker's Textbook of Microbiology, 11th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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