Frederick Griffith (1879-1941), who was born in Hale, Cheshire County, England and who attended the Liverpool University, was a British bacteriologist whose focus was the epidemiology and pathology of bacterial Pneumonia. In January, 1928 he reported what is now known as Griffiths Experiment, the first widely accepted demonstration of bacterial transformation, where a bacterium distinctly changes its form and function. Griffith succumbed to his death around the year 1941 due to the air raid.
His Purpose and what he derived?
Griffith showed that Streptococcus pneumonia, could transform from one strain into a different strain. The observation was attributed to an unidentified transforming principle of transforming Factor. This was later identified as the stuff of life “DNA”
Griffith’s experiment, reported in 1928, was one of the first experiments suggesting that bacteria are capable of transferring genetic information through a process known as transformation. Griffith went about deriving his results by means of using two strains of Pneumoccocus (Streptococcus pneumonia) bacteria which he used to infect several mice. A type smooth strain and a type rough strain. The smooth strain has its components covered by a polysaccharide capsule, which gives it the ability to live in adverse conditions and divide rapidly through a process called Binary fission. Adverse conditions in the context of this experiment would mean “protection from white blood cells” The third line of defense’s inability to phagocytize the bacteria subsequently results in the death of the mice because the capsule accommodates for the rapid growth of the same cell. Bacterial cells usually have a target organ to which it chooses to disintegrate, and in the case of abundance, the more the number of bacterial cells the more likely the host is going to succumb to it death.
How the Experiment was Set up?
The experiment was set up by means of inoculating mice with different forms of the same bacteria but with varying strains. The first mouse was inoculated with the rough strain of the streptococcus bacteria and the mice lived. The second mouse was inoculated with the smooth strain (virulent strain) and the end result was the death of the mouse. The third mouse was inoculated with the heat killed smooth strain bacteria and the mouse lived. The emphasis to the transformation principle was given when Griffith infused the rough strain and the heat killed smooth strain and inoculated the mouse which further resulted in the death of the mouse. Griffith was unknown of the reason why the mouse died, but with scientific reasoning, he brought up the idea that the combined Pneumonia bacteria used a transforming principle to activate the virulence, which subsequently then was named the transformation principle.
Why did the Heat killed smooth Bacteria show no effect towards the Mice?
Just like how we humans function well on optimal temperature, bacteria too have a set temperature to work at its potential. In the context of this experiment the virulent smooth strain pneumonia bacteria was covered by a capsule which consisted of a polysaccharide, a sugar. The introduction of heat disintegrated the capsule, subsequently making it prone to phagocytosis by the white blood cells. The rough strain didn’t comprise of a capsule which explains why it showed no effect towards killing the mouse. The introduction of heat denatured the components of the smooth train which as a result didn’t give the heat killed smooth strain bacteria, not enough potential to kill the mouse.
Contribution to our Knowledge
Shedding Light to the Transforming Principle
Upon research and experimentation on Pneumococcal Streptococcal bacteria-Griffin pointed out that the information in bacterial cells could somehow be transferred between different strains of bacteria. This was long before the discovery of DNA and was an inspired piece used by Avery, Mc Carty and Mc leod to emphasize more on what are primarily the subunits of life. Griffith also wrote a paper in 1928 with regards to his experiment and how he came up with the derivation of the term “Transforming principle”. Apart from Griffins inspiring research, his findings led to the pivotal beginning of molecular biology. In 1952, other researches with the insight gained from Griffiths experiment, further brought meaning to what is the fundamental and the subunits of life by creating their own sets of experiments all interconnected with this experiment in the process of deriving the form, structure and the function of DNA in one way or another.