Linear Cell Mass Increase during the Cell Cycle of Escherichia coli

Abstract

Linear increase of cell mass of undivided cells was determined during the division cycle of Escherichia coli B/rA. Synchronous growth was obtained by selection of cells from exponentially growing populations after velocity sedimentation in sucrose density gradients. Cell mass was calculated as a product of mean cell volume and buoyant density that were measured at intervals during synchronous growth. A liner increase in cell mass was observed in two different growth media which had doubling times of 40.0 and 30.1 minutes. The results support the theory of constant linear increase of cell mass throughout the division cycle.