What did Griffiths discover using infected mice?

Griffith's discovery involved the transformation of bacteria, demonstrating that genetic material could be transferred between different bacterial strains. In his classic experiment with mice and two strains of Streptococcus pneumoniae—one pathogenic and one non-pathogenic—he found that when the non-pathogenic strain was mixed with heat-killed pathogenic bacteria, the non-pathogenic bacteria could acquire the ability to cause disease. This indicated that some component from the dead pathogenic bacteria was taken up by the live non-pathogenic bacteria, leading to a change in their characteristics. This transformative process highlighted the role of DNA as the genetic material responsible for heredity and genetic change, laying the groundwork for future molecular genetics research. Thus, the discovery of genetic material transfer between bacteria is a pivotal moment in the understanding of genetics, underscoring the ability of microorganisms to exchange genetic information and adapt.