Imaging the Cell Cycle of Pathogen E. coli During Growth in Macrophage

The study of the bacterial cell cycle at the single cell level can not only give insights on the fitness of the bacterial population but also reveal heterogeneous behavior. Typically, the DNA replication, the cell division, and the nucleoid conformation are appropriate representatives of the bacterial cell cycle. Because bacteria rapidly adapt their growth rate to environmental changes, the measure of cell cycle parameters gives valuable insights for the study of bacterial stress response or host-pathogen interactions. Here we describe methods to first introduce fluorescent fusion proteins and fluorescent tag within the chromosome of pathogenic bacteria to study these cell cycle steps; then to follow them within macrophages using a confocal spinning disk microscope.