Macromolecule synthesis of Escherichia coli BB at a lower or transient growth state.

Macromolecule synthesis in Escherichia coli BB at lower growth rates was investigated. The results indicate that a deviation in ribonucleic acid (RNA) content per cell at a lower growth rate from the exponential relationship to a specific growth rate is entirely attributable to the presence of nonviable cells, in which the RNA content is lower than in viable cells. Based on this fact, a mathematical expression of macromolecule contents versus specific growth rate was devised. Moreover, continuous changes in macromolecule content during unbalanced growth from late-logarithmic phase to stationary phase were measured. Although growth rates changed continuously, the data on deoxyribonucleic acid (DNA) or RNA content versus the specific growth rate calculated from the increments in cell number satisfactorily fitted the exponential lines obtained under balanced growth at a higher growth rate. However, no such relationship was observed in the plot of DNA or RNA content versus the specific growth rate calculated from the increments in optical density.