Transformation is a experiment which was performed by Frederick Griffith in 1928 in order to provide evidence for the genetic material.
In his experiment he used bacteria streptococcus pneumoniae. Two strains were taken for this experiment.
1. S-III
2. R-II
Features of S-III strain :-
A. Smooth
B. Capsulated
C. With mucous coat
D. This strain was pathogenic or virulent.
E. This can cause pneumonia.
F. Shiny colonies can be produced by them.
Features of R-II strain :-
A. Rough
B. Non - capsulated
C. This strain is of non virulent type hence they do not cause pneumonia.
D. In this coat is absent.
E. Rough colonies are produced by them.
Experiment I :-
He injected S-III strain in the mice then the mice died as this strain is virulent. He got the expected result in this experiment.
Experiment II :-
This time he injected R-II type strain into the mice and then he got the expected result i.e. mice lived as because this was nonvirulent type strain.
Experiment III :-
Now the S-III or the smooth strain type bacteria were heat killed and then injected into the mouse. The mice lived this time as well, also Griffith expected because normally heat killed bacteria do not cause pneumonia.
Experiment IV :-
R-II strain (living) which normally do not cause pneumonia and S-III strain (heat killed) which also do not cause pneumonia were injected then the mice died. He was very surprised with this result.
Conclusion:-
Result of the 4th experiment was very surprising. After working on the dead mice body he got the normal S-III strain in it. On the basis of this result he concluded that some genetic material from bacteria of the S-III strain were transferred to R-II that's why the rough strain also converted into S-III.