Fig. 2.

Mineral encasement of a bacterial cell. (a) Bacterial cell (green) surrounded by a microenvironment (light blue) created by an extremely low Reynolds number and/or sheaths, capsules, slimes, biofilm matrices or extracellular polymeric substances. (b) Accumulation, stabilization and slow diffusion of ions within the microenvironment close to the cell occurs from metabolism and cell-surface interactions creating a high local ion concentration (dark blue). (c) Within the cell-surface vicinity, at a high ion concentration, the equilibrium is shifted in favour of supersaturation and thus precipitation (grey shapes). (d) Onset of precipitation can lead to the breakdown of the microenvironment and, along with the degradation of some extracellular organic components, leaves behind a mineral-organic phase encasing the cell (grey shapes).