A LuriaDelbruck fluctuation test was performed to assess the

A Luria/Delbruck fluctuation test was performed to assess the frequency that T1 -resistant E. coli mutants arise in a culture. Four different E. coli cultures were allowed to grow for 6 hours, and then T1 page was added. Cells were then plated and the number of phage resistant bacteria was tabulated. Explain how the results of this experiment support the hypothesis that the environment selects from pre-existing spontaneously occurring mutations.

Solution

The results of this experiment support the hypothesis that the environment selects from a pool of pre-existing spontaneously occurring mutations; as there is a marked variation in the number of bacteria (E.Coli) in the four different cultures varying from; 3 to 370. This is due to high variance in the number of mutations which might have occurred at any time during the liquid culture phase that accumulate exponentially. Thus the mutations arose randomly leading to such a high variance.