Question

First transformation experiment on bacteria was performed on

• A. Escherichia coli
• B. Salmonella typhimurium
• C. Pasteurella pestis
• D. Streptococcus pneumoniae

Answer 1

Answer: (D)

Streptococcus pneumoniae

Transformation is the transfer of genetic material from one bacterial strain to other without establishing a physical contact. F. Griffith infected mice with a mixture of virulent (SIII) and non-virulent strains (RII) of Streptococcus pneumoniae. Heat-killed SIII did not cause an infection but a mixture of heat-killed SIII and living RII strains caused infection because a transforming substance was transferred from heat-killed strain to nonvirulent strain causing non-virulent strain to transform into the virulent form. There was no direct physical contact between virulent and non-virulent strains during transfer of genetic material.