Structured Silicon for Revealing Transient and Integrated Signal Transductions in Microbial Systems

by Gao et al.

Sci. Adv. 14 Feb 2020: Vol. 6, no. 7, eaay2760

DOI: 10.1126/sciadv.aay2760

Xiang Gao et al. conducted a study on various B. subtilis biofilms to understand bacterial response to transient physical stress and to determine the influence of calcium dynamics on mechanical properties, particularly stiffness.

Nanoindentation was performed using a Hysitron BioSoft in-situ indenter (Bruker, Minneapolis, MN) mounted on a Leica SP5 confocal microscope. The cocultured biofilms (with Si nanowires) were stimulated using the confocal microscope, and a laser (592 nm) was used to scan a region of interest of 300×300 µm2. The stiffness of the biofilm on structured silicon was measured at different locations with and without intercellular calcium signaling. A Hertzian contact model of a rigid sphere indenting into an elastic half space was used to analyze nanoindentation results. The laser-stimulated part of biofilm exhibited a reduction in stiffness (reduced by 20.8%) compared to unstimulated ones due to modulus alteration by coupling between calcium and biofilm.

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  • Bacterial response to transient physical stress
  • The influence of calcium dynamics on the mechanical properties—esp. stiffness—of B. subtilis biofilms on structured silicon
  • Functional integration of Si materials & bacteria



  • Captured a previously unidentified form of intercellular calcium signaling within the biofilm
  • Suggests that Ca2+ propagation and dynamics can influence a biofilm’s intrinsic mechanical properties (i.e. elastic modulus, viscoelasticity)
  • Suggests that chemical-mechanical coupling plays an important role in bacterial response under stressful conditions


Biofilms, Calcium Signalling, Microbial Biofilms, Signal Transduction, Silicon, Si Nanowires, Synthetic Biology