Benzerara et al. 10.1073/pnas.0603255103. |
Supporting Figure 6
Supporting Figure 7
Supporting Figure 8
Supporting Figure 9
Supporting Figure 10
Supporting Figure 11
Supporting Figure 12
Fig. 6. C K-edge near-edge x-ray absorption fine structure (NEXAFS) spectra of reference compounds. Spectra of Caulobacter crescentus and Bacillus subtilis display four main peaks (a: 285.2 eV, b: 286.8 eV, c: 288.2 eV, and e: 289.5 eV) at the same energy position. Extracellular polymeric substances produced by C. crescentus and B. subtilis cells display similar NEXAFS spectra with two main peaks at b: 286.8 eV and d: 288.6 eV.
Fig. 7. Spectromicroscopy analysis of Lake Van calcified microorganisms and biofilms at the C K-edge. Images were taken at 280 eV (below the C K-edge), 288.2 eV (protein absorption), and 290.2 eV (carbonate absorption). Extracellular polymeric substances and protein display peaks at different energy positions.
Fig. 8. Spectromicroscopy analysis of Lake Van calcified microorganisms at the C K-edge. Imaging of the same areas by transmission electron microscopy (TEM) and scanning transmission x-ray microscopy (288.2 eV). The microbe (in Lower Left) is not distinguishable from aragonite clusters by TEM alone.
Fig. 9. Lake Van microbialite carbonates stained by Con A labeled with fluorescein isothiocyanate. Epifluorescence (Left) and phase contrast (Right) microscopy images of different areas of the microbialites are shown. Background fluorescence (aragonite fluorescence) has been subtracted by comparison with Lake Van samples not stained with Con A. Note the pervasive fluorescence associated with the carbonate precipitates.
Fig. 10. Spectromicroscopy at the carbon and nitrogen K-edges on experimentally calcified Ramlibacter tataouinensis bacteria stored in this state for 4 years. (a) Scanning transmission x-ray microscopy image taken at 288.2 eV, i.e., the resonance energy of amide groups in proteins. (b) Map of carbon functional groups absorbing at 288.2 eV, i.e., mostly proteins. (c) Carbon K-edge NEXAFS spectra of calcified R. tataouinensis cells (or fragments of cells) and polymers surrounding the cells. Dashed lines are at 288.2 (peptidic bond) and 288.6 eV (carboxylic groups mostly in polysaccharides). (d) Nitrogen K-edge NEXAFS spectra of calcified R. tataouinensis cells, noncalcified C. crescentus cells, and cells from Lake Van. Vertical dotted lines at 399 eV, 399.9 eV, and 401.2 eV show correlations between the spectra.
Fig. 11. Additional high-resolution TEM images showing the amorphous layer surrounding the Lake Van aragonite crystals. The thickness was observed to vary from 2 nm to 10 nm.
Fig. 12. Structure of Lake Van microbialites (see also refs. 1–3). The samples were collected within the wall of the microbialite. SEM picture shows the typical texture at this location site.
1. Kempe, S., Kazmierczak, J., Landmann, G., Konuk, T., Reimer, A. & Lipp, A. (1991) Nature 349, 605–608.
2. Kazmierczak, J. & Kempe, S. (2003) Naturwissenschaften 90, 167–172.
3. López-García, P., Kazmierczak, J., Benzerara, K., Kempe, S., Guyot, F. & Moreira, D. (2005) Extremophiles 9, 263–274.