Figure 4

Scanning electron micrographs (SEM) of samples from the Tomba degli Scudi. (a) Purified spores from Bacillus cereus (sample 10) isolated from the white deposition of the western wall. (b) Spheroidal element from the western wall covered of white deposition (see also Fig. 1d) corresponding to CaCO₃. (c) Spores of a mould from the thick white deposition of the eastern wall (see Fig. 1e). (d) A microorganism in the thick deposition in the eastern wall is producing CaCO₃ (see Figure S4b). (e) CaCO₃ produced by a pure culture of sample 7 grown on YPD supplemented with urea (see also Figure S6). (f) CaCO₃ produced by a pure culture of sample 10 in YPD supplemented with urea; white arrows indicate the spores of this microorganism mixed with the CaCO₃.