Fig. 3.

TEM analysis of bacterial calcium carbonate precipitates. a After 17 h incubation time bacterial cells (bc) are covered by nanoparticle precipitates; b SAED pattern of the structures in a showing diffuse haloes demonstrating the amorphous nature of such precipitates; c after 48 h incubation time, larger precipitates made up of nanoparticles are observed around the bacterial cells; d the $\left[\overline{4}\overline{4}1\right]$-zone axis SAED pattern of precipitates in c shows they are single-crystalline calcite (Cc); e detail of calcite precipitates ($\left[42\overline{1}\right]$-zone axis SAED pattern in inset) formed around bacterial cells. Note their nanogranular porous structure