Modes of Bacterial Aging and Death

Currently, “biological aging” is well defined in human beings and multicellular organisms, and is one of the largest risk factors for most diseases. However, in single cell organisms there has been a sequence of various definitions. My research focuses on understanding the cellular processes responsible for senescence and death in E. coli bacteria as well as identifying cellular characteristics of aging. We employed an experimental setup consisting of a microfluidic device designed to trap single-cells while continuously supplying them with nutrients, allowing us to acquire images of the trapped cells. Analysis of these images provides long-term single-cell measurements of cell-size and protein content, which are then used to uncover aging effects and determine modes of cell death. Our data acquired thus far reveal two different phenotypes of cell death: 1. Part of the cells maintain their bacterial chromosome and enter a non-dividing phase. 2. A subset of the population loses its chromosome and so all cellular functions are obstructed. Our results indicate aging in all strains, which is marked by the increase in death rate with time. In addition, by comparing wild type and an ATP synthase E. coli mutant, we found different average lifetimes prior to undergoing these transitions.