Author interview — Sree is a graduate student with Dr. Tapomoy’s group at NCBS. His research explores fundamental principles of how the physical microenvironment regulates growth, motility, and morphology across different biological scales.
This research is the first to show that the mechanical environment of a bacterium can directly act as a potent selective pressure by favouring certain species over others in a cell shape-dependent manner.
We show that even beyond the conventional domains of genetic mutations and chemical signalling, there exists a rich class of regulation through the mechanical environment that decides the fate of microbial communities.
– Dr. Tapomoy Bhattacharjee
For over three hundred years, microbiologists have looked at bacterial growth using experimental systems like liquid broths and flat plates. However, these do not capture the complexity of their natural habitats such as soil, infected tissues, and mucus. In our study, we bridged this gap by engineering mucus-like 3D systems to culture bacteria. Using this, we found that the structure of bacterial colonies in 3D space is dictated by the shape of a single cell – while rod-shaped bacteria form elongated and spread out colonies, spherical bacteria form compact and rounded colonies. Remarkably, this shape-dependent pattern allows rod-shaped bacteria to grow more successfully in highly confined 3D environments, helping them outcompete the spherical bacteria. Hence, our work provides the first-such experimental evidence that physical confinement plays a selective role in determining bacterial growth fitness. This completely alters the way we traditionally think about how microbial populations survive and adapt across diverse ecological settings such as soil, aquifers, mucus, and infected tissues. Importantly, our research provides a new framework for understanding how the mechanical properties of an environment can actively regulate its resident biological matter.
Reference: Sreepadmanabh, M., Ganesh, M., Sanjenbam, P. et al. Cell shape affects bacterial colony growth under physical confinement. Nat Commun 15, 9561 (2024). https://doi.org/10.1038/s41467-024-53989-6
