Biofilms are multicellular microbial communities that encase themselves in an extracellular matrix (ECM) of secreted biopolymers and attach to surfaces and interfaces. Bacterial biofilms are detrimental in hospital and industrial settings, but they can be beneficial, for example, in agricultural as well as in food technology contexts. An essential property of biofilms that grants them with increased survival relative to planktonic cells is phenotypic heterogeneity, the division of the biofilm population into functionally distinct subgroups of cells. Phenotypic heterogeneity in biofilms can be traced to the cellular level; however, the molecular structures and elemental distribution across whole biofilms, as well as possible linkages between them, remain unexplored. Mapping X-ray diffraction across intact biofilms in time and space, we revealed the dominant structural features in Bacillus subtilis biofilms, stemming from matrix components, spores, and water. By simultaneously following the X-ray fluorescence signal of biofilms and isolated matrix components, we discovered that the ECM preferentially binds calcium ions over other metal ions, specifically, zinc, manganese, and iron. These ions, remaining free to flow below macroscopic wrinkles that act as water channels, eventually accumulate and may possibly lead to sporulation. The possible link between ECM properties, regulation of metal ion distribution, and sporulation across whole, intact biofilms unravels the importance of molecular-level heterogeneity in shaping biofilm physiology and development.
|Original language||American English|
|Journal||Proceedings of the National Academy of Sciences of the United States of America|
|State||Published - 25 Jan 2022|
Bibliographical noteFunding Information:
Berlin fu€r Materialien und Energie and at beamline ID13 at the European Synchrotron Radiation Facility. We thank the Helmholtz-Zentrum Berlin (HBZ) and the ESRF for provision of synchrotron radiation facilities and for financial support. We thank the Electron Microscopy Facility of Max Planck Institute of Molecular Cell Biology and Genetics (MPI-CBG) for support and use of equipment and reagents and Daniel Werner at the Max Planck Institute of Colloids and Interfaces (MPIKG) for X-ray measurements. We thank Jiliang Liu for ESRF ID13 beamline assistance at ESRF. Special thanks to Prof. Sigal Ben Yehuda for insightful discussions, Yosef Edery Aharony for his contribution with data sorting and image analysis, and Daniel Rosenblatt for assistance with the image analysis. D.N.A. acknowledges the support of the Kaete Klausner PhD scholarship and M.G. acknowledges the support of the Neubauer Foundation for the PhD fellowship.
© 2022 National Academy of Sciences. All rights reserved.
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