Fig. 4: Nanoanalytical spectroscopy investigations of M. sedula grown on NWA 7034.

a The HAADF-STEM image of a cell of M. sedula used for high-resolution investigations and electron energy loss spectroscopy (EELS) analysis. b, c Representative HR-STEM of biogenic crystalline mineral deposits inside the cell of M. sedula. Insets in panels represent the fast fourier transforms (FFTs) consistent with the phases of tetragonal Mn3O4-type nanoassemblages embedded into Fe3O4. d EDS false colors composed mineral map of a cell of M. sedula (Mn-red, P-green, Fe-blue). The next mineral phases can be visualized: intracellular mixture of Mn-bearing phases (Mn3O4, mixed MnxSiyOz-containing phases (magenta); intracellular Fe-bearing phase Fe3O4 (blue); and mixed Fe, Mn, Al phosphates in the outer crust layer (cyan). Corresponding inter-atomic spacing (d-values) are presented in Supplementary Table 4. e Corresponding Fe L2,3-edge in the EELS acquired from the crust outer layer (shown as red line) and the intracellular nanocrystalline deposits (shown as green line) of the M. sedula cell.