How Did Griffith Find The Transforming Factor For The Growth Of Bacteria

A bacterium of choice by Frederick Griffith was S. pneumoniae cells also known as Pneumococcus bacteria. This is due to the growth of bacteria inside the body of a host regardless in the form of either solid or liquid cultures. In 1928, Frederick Griffith studied and published his findings on the different strains of Pneumococcus bacteria. There were 2 in particular that looked different; S and R. The R colonies has rough surface whereas the S colonies have smooth surface. Intrigued by the experiment, Avery, MacLeod and McCarty decided to reaffirm Griffith’s experiment to find the transforming “principle”. Griffith used mice as a test subject, Avery and his colleagues this time used test tube assay.

1. Detergent was used to lyse the heat-killed S cells in which 2 layers of component were shown which was cellular debris below and lysate on the surface.The lysate contains of components RNA, DNA, polysaccharide coat and protein. The lysate was then extracted to be used as the transformation assays in which it worked and showing that the heat-killed S lysate could change R to produce S bacteria. They concluded that the lysate contains the transforming factor.

2.
They then conducted a test on each of the component available in the lysate to identify the transforming factor. They first incubated the heat-killed S lysate with an enzyme, known as SIII, in which it consumed the polysaccharide coat surrounding the bacteria. Next, they tested for the transforming factor on the polysaccharide coatless S lysate. They found that the polysaccharide coatless S lysate was still able to transform producing bacteria. The R strain was producing a new S polysaccharide coat from the