Understanding how bacteria grow and control their division is a fundamental question, yet our understanding of these processes is incomplete. I will describe several methodologies we developed to extract biological insights into these processes from single-cell measurements of cell size and timing of key cell cycle events, which we applied to data of E. coli and M. tuberculosis (Mtb).

First, I will show analysis suggesting that E. coli grows super-exponentially during the cell cycle, while, surprisingly, Mtb cells grow approximately linearly. Next, I will use the framework of causal inference to obtain strong constraints on causality from (conditional) correlations. In this way we find that in E. coli cell division is always coupled to DNA replication, albeit in a manner that depends on the growth conditions. For Mtb, we find that control of DNA replication cycles is distinct from the E. coli paradigm.