Answer:
In 1928, Frederick Griffith did Griffith's experiment suggesting the ability of transformation present in bacteria which means that bacteria are capable of transferring genetic information.
In Griffith's experiment, a DNA was isolated as the material that communicated this genetic information. With his experiment Griffith developed the first vaccine against pneumonia.
Griffith has contributed to biology in a very distinct way with his experiment and discovered an important feature of DNA that is transformation. This feature of transformation in DNA is widely used in medical field for treatment or development of vaccines for several diseases.