Following a single bacterium along the growth-curve

Bacteria in natural environments go through periods of starvation punctuated by the arrival of fresh nutrients that then get depleted again as cells grow and divide. Many mechanisms have therefore evolved to help cells weather busts and exploit booms. Traditionally these have been studied by inoculating cultures of stationary phase cells into fresh media and following them along the growth curve back into stationary phase. However, batch assays consider average properties of cells, while single cell studies have revealed great cell-to-cell heterogeneity during stress, e.g. by making a small fraction of cells persistent to drugs.  However, it has been difficult to track individual cells along the growth curve to determine the progression of events or correlations between how cells enter and exit dormancy. To address this, we have developed a platform for tracking >10^5 parallel cell lineages in dense and changing cultures, independently validating that the imaged cells closely track the batch population. This provides a microcosm of bulk growth with exceptional resolution and control, while enabling conventional bulk assays on the same culture. In this talk, I will discuss the steps in the method-development, and how we used this platform to probe the size-regulation principles of E. coli during entry into and exit from stationary phase, and observed trade-offs between the behaviors entering and exiting stationary phase.

Host: Dr Alessia Lepore