Question

Write a brief note on Griffith’s experiment. What was the conclusion drawn from this experiment?

Answer 1

Frederick Griffith conducted experiments on Streptococcus pneumoniae, which occurs in two strains: the smooth virulent strain (S) and the rough avirulent strain (R).

When R strain bacteria were injected into mice, the mice remained healthy. When S strain bacteria were injected, the mice developed pneumonia and died. Injections of heat-killed S strains did not kill the mice. However, when a mixture of live R strain and heat-killed S strain was injected into mice, the mice died and live S strain bacteria were recovered from their bodies.

Conclusion: Griffith concluded that the heat-killed S strain released a transforming principle that converted the non-virulent R strain into the virulent S strain. This process is called transformation.