Figure 7. Energy-dispersive X-ray spectroscopy of the serum granulations reveals a broad spectrum of compositions similar to NB.

Serum granulations (pellets) were obtained as before from untreated serum (A and E) or after addition of either CaCl₂ (B and F), Na₂HPO₄ (C and G), or a combination of both (D and H) to the indicated serum. EDX spectra were also obtained for NB cultured from HS (I) or for two NB strains cultured in FBS (J and K). Commercial reagents of CaCO₃ (L), calcium phosphate labeled as Ca₃(PO₄)₂ (M), and HAP (N) were used for comparisons. Serum granulations were also prepared by adding CaCl₂ to FBS followed by incubation for 1 hour (O) or overnight (P) at room temperature. The following Ca/P ratios were obtained: (B) 1.31; (C–E) 1.33; (F) 1.86; (G) 1.3; (H) 1.24; (I) 1.28; (J) 1.36; (K) 1.31; (M) 1.31; (N) 1.63; (O) 5.42; and (P) 1.24. In (A) and (L), Ca and P were not detected. The presence of C in some samples might be attributed in part to the formvar carbon-coated grids used as support for the analysis.