Fig. 4. Dot-blot hybridization of DNA extracted from December samples from Cell 1 (A and B) and Cell 4 (C and D). Amplified 16S rDNA from A. ferrooxidans (A1 and C1), A. thiooxidans (A2 and C2), Archaeoglobus fulgidus (B1 and D1), and Ferroplasma acidarmanus (B2 and D2) was hybridized by using fluorescein-labeled rDNA from Fe precipitates.