Cell Size and Metabolic Activity at Various Phases of the Bacterial Culture Cycle

Abstract

By measurements of fixed and stained samples of Escherichia coli, Salmonella gallinarum, and S. pullorum at various periods of the culture cycle, the authors have studied variations in mean cell volume and related these variations to metabolic activity as measured by CO pro-duction. Metabolic activity, cell volume and cell division rate all exhibit a definite and orderly relationship in the life cycle reaching a peak in the order named. The high metabolic activity characteristic of the phase of physiological youth is only in part accounted for by increased cell volume. The presence of a fermentable sugar seems to stimulate more rapid cell division and under certain conditions leads to a larger cell size during later phases of the culture cycle.