Hello aspirant,

Griffith's experiment is based on the bacteria can get DNA through a process of transformation.Griffith the name of the inventor of this bacteria he use his bacteria in the mic similar to humans.He used a type III-S (smooth) and type II-R (rough) strain .III-s Strain protect the immunity system of the mice.II R strain not protect the immune system so mice will die.Now we are using this principle III-S is not harmful it protect over immune system.

I hope this information helps you,

Thank you