Figure 7

Identification of biological microstructures using ToF–SIMS molecular imaging in Target Area 3 (TA3). Groups G1, G3, G4, and G9 outline different oval elements (< 80 microns) that are associated with parallel straight structures longer than 500 microns. Interestingly, groups G2, G5, and G6, which have been associated with phytochemicals as well as PAHs, occur in the mineral matrix that encloses the biological structure. Such a distribution suggests that the microbial structure had been transported or was thriving in a water mass that was enriched in refractory organic compounds such as PAHs and some phytochemicals. The RGB overlay shows that the biological structure has compositional changes that represent sulfate biomineralization (Na₃SO₄⁺, and K₂NaSO₄⁺), as well as sphingolipid (C₄H₁₀NO⁺) and acylglyceride fragments (C₁₆H₃₃O₂⁺). The PAH intensity image was obtained by adding the intensities of different PAHs such as C₉H₇⁺, C₁₀H₈⁺, C₁₁H₉⁺, C₁₂H₈⁺, C₁₃H₉⁺, and C₁₄H₁₀⁺ (see Supplementary Table 3).