The roles of intracellular and extracellular calcium in Bacillus subtilis biofilms

In nature, bacteria reside in biofilms– multicellular differentiated communities held together by an extracellular matrix. This work identified a novel subpopulation—mineral-forming cells—that is essential for biofilm formation in Bacillus subtilis biofilms. This subpopulation contains an intracellular calcium-accumulating niche, in which the formation of a calcium carbonate mineral is initiated. As the biofilm colony develops, this mineral grows in a controlled manner, forming a functional macrostructure that serves the entire community. Consistently, biofilm development is prevented by the inhibition of calcium uptake. Our results provide a clear demonstration of the orchestrated production of calcite exoskeleton, critical to morphogenesis in simple prokaryotes. [Display omitted] •The orchestrated formation of calcite scaffolds supports the morphogenesis of microbial biofilms•A novel subpopulation—mineral-forming cells—is essential for biofilm formation•This subpopulation contains an intracellular calcium-accumulating niche, supporting the formation of calcium carbonate•Intracellular calcium homeostasis and calcium export are associated with a functional biofilm macrostructure Microbiology; Microbiofilms; Cell biology