Physiology of the Bacterial Cell Cycle: Historical Milestones and Methodological Advances Shaping Current Understanding

The bacterial cell cycle, encompassing the coordinated events of chromosome replication, segregation, cell growth, and division, remains one of the central unresolved questions in microbial physiology. Despite decades of intensive research, fundamental gaps persist in our understanding of how bacteria integrate molecular signals, physical constraints, and environmental inputs to sustain precise and adaptable cell cycle programs. New layers of regulation and complexity continue to emerge, driven by conceptual advances, theoretical modeling, and transformative technologies that are reshaping how the field approaches bacterial organization and control.The molecular framework of the bacterial cell cycle rests on landmark conceptual contributions, including Replicon Theory, models of replication initiation and cell size homeostasis, and the characterization of the machinery governing chromosome segregation and division, that continue to generate unresolved questions and competing hypotheses. How do bacteria robustly couple DNA replication to division across widely varying growth conditions? What molecular mechanisms set and adjust initiation mass? How is the spatial organization of the chromosome actively maintained and remodeled throughout the cell cycle? Model organisms such as Escherichia coli, Bacillus subtilis, and Caulobacter crescentus have been central to addressing these questions, while growing interest in non-model and environmentally relevant bacteria continues to reveal unexpected diversity in cell cycle strategies.A particularly dynamic frontier is the view of the bacterial cell as a physical system, one in which the mechanical properties of the cytoplasm, nucleoid organization, molecular crowding, and intracellular biophysics actively shape cell cycle outcomes. Advances in super-resolution microscopy, single-cell tracking, microfluidics, Hi-C chromosome conformation capture, and cryo-electron tomography now enable quantitative, spatially resolved measurements of cell cycle events at unprecedented resolution. In parallel, biophysical modeling and integrative theoretical frameworks are generating testable predictions of cell cycle behavior from first principles, placing bacterial physiology at a productive intersection of molecular biology, physics, and systems science.This Research Topic aims to capture current progress and open questions in bacterial cell cycle research, integrating molecular, biophysical, and systems-level perspectives. We invite original research, reviews, and perspectives addressing, but not limited to, the following themes:-Mechanisms of replication initiation, elongation, and termination: current models and unresolved questions-Chromosome organization, condensation, and segregation dynamics-The divisome and cell constriction: architecture, regulation, and open mechanistic questions-Cell size homeostasis and the coupling of replication timing to growth-Spatial regulators of division site positioning (e.g., Min system, nucleoid occlusion)-Asymmetric division and cell cycle–coupled differentiation in model organisms-The bacterial cell as a physical system: cytoplasmic biophysics, nucleoid mechanics, and physical constraints on cell cycle progression-Quantitative, biophysical, and theoretical frameworks for cell cycle analysis-Emerging methodologies: microfluidics, super-resolution imaging, cryo-ET, and single-cell tracking-Cell cycle diversity and adaptation in non-model and environmentally relevant bacteria-Links between cell cycle dysregulation, antibiotic tolerance, and persistenceBy integrating molecular, biophysical, and systems perspectives on both established principles and open questions, this collection aims to map the current frontiers of bacterial cell cycle research and define the challenges that will shape its next chapter. Topic editors: Julia Grimwade, John Herrick, Masamichi Kohiyama Source: https://www.frontiersin.org/research-topics/81594/physiology-of-the-bacterial-cell-cycle-historical-milestones-and-methodological-advances-shaping-current-understanding