Mia Park and Denise Mondelo

Abstract:

Many mutations occur in the lab that can either benefit or hinder the growth of bacteria. However, certain mutations do not present clear outcomes: some can be neutral in effect and it can be difficult to measuring changes in fitness as well. Previously, the McLoon lab performed an evolution experiment, where a Bacillus subtilis strain was adapted to grow in a shaking LB broth for approximately 300 generations. Following this, our lab has sequenced 53 isolates from the growth adaptation experiment, resulting in the finding that mutations occurred in the gene deoR in 26 out of 53 of our laboratory-adapted B. subtilis strains. The DeoR repressor controls the expression of the dra, nupC, and pdp genes, which control the uptake and catabolism of pyrimidine nucleic acids, which are used as building blocks and sometimes as nitrogen sources by B. subtilis. We have performed experiments such as growth curves and competitions to quantify the growth of the specific strains with a deoR mutation, and current results are inconclusive. We will continue to seek to understand the effects of the deoR mutation in the different strains to determine why so many independent deoR mutations occurred during laboratory adaptation.