THE ROLES OF NUCLEOID ASSOCIATED PROTEINS IN THE GROWTH RATE OF ESCHERICHIA COLI

Single-cell organisms increase the number of cells by repeating the cell cycle, consisting of the chromosomal replication and the cell division, on log phase. A bacterial genome organizes a nucleoide with nucleoid associated proteins (NAPs) in a cell. Escherichia coli has 6 species of NAPs: H-NS, Fis, HU, StpA, Dps, and IHF, which also function as regulators for the gene expression and the chromosome replication. In this study, I show that the isolated NAP gene mutants changed the parameters of E. coli growth rate. First, I measured the turbidity of E. coli culture, incubated at 37℃, at intervals of 15 minutes for 72 hours. The growth rate was calculated at every 15 minutes and plotted to OD_600, the turbidity value. The plot showed the constant growth rate in light turbidity (～0.2 of OD_600) and the decrease in the growth rate on log phase, finding two important values, the initial growth rate and growth deceleration, for characterization of E. coli growth. Both the initial growth rate and the growth deceleration were changed by growth temperature and reached the maximum at 37℃. Among the isolated E. coli mutants, fis-single mutant increased both the initial growth rate and the growth deceleration and dps-single mutant indicated the opposite result. I have just analyzed the isolated multigene knockout strain MCS01401, mutating fis, hupA, hupB, stpA, and dps genes on its genome