Department of Chemical and Biological Engineering, South Dakota School of Mines and Technology, Rapid City, SD 57701, USA.
J Basic Microbiol. 2010 Apr;50(2):160-70. doi: 10.1002/jobm.200900239.
An aqueous mixture of goethite, quartz, and lead chloride (PbCl(2)) was treated with the sulfate-reducing bacterium, Desulfovibrio desulfuricans G20 (D. desulfuricans G20), in a medium specifically designed to assess metal toxicity. In the presence of 26 muM of soluble Pb, together with the goethite and quartz, D. desulfuricans G20 grew after a lag time of 5 days compared to 2 days in Pb-, goethite-, and quartz-free treatments. In the absence of goethite and quartz, however, with 26 microM soluble Pb, no measurable growth was observed. Results showed that D. desulfuricans G20 first removed Pb from solutions then growth began resulting in black precipitates of Pb and iron sulfides. Transmission electron microscopic analyses of thin sections of D. desulfuricans G20 treated with 10 microM PbCl(2) in goethite- and quartz-free treatment showed the presence of a dense deposit of lead sulfide precipitates both in the periplasm and cytoplasm. However, thin sections of D. desulfuricans G20 treated with goethite, quartz, and PbCl(2) (26 microM soluble Pb) showed the presence of a dense deposit of iron sulfide precipitates both in the periplasm and cytoplasm. Energy-dispersive X-ray spectroscopy, selected area electron diffraction patterns, or X-ray diffraction analyses confirmed the structure of precipitated Pb inside the cell as galena (PbS) in goethite- and quartz-free treatments, and iron sulfides in treatments with goethite, quartz, and PbCl(2). Overall results suggest that even at the same soluble Pb concentration (26 microM), in the presence of goethite and quartz, apparent Pb toxicity to D. desulfuricans G20 decreased significantly. Further, accumulation of lead/iron sulfides inside D. desulfuricans G20 cells depended on the presence of goethite and quartz.
将针铁矿、石英和氯化铅（PbCl(2)）的水相混合物用硫酸盐还原菌脱硫弧菌 G20（D. desulfuricans G20）处理，该培养基是专门设计用来评估金属毒性的。在存在 26 μM 可溶性 Pb 的情况下，与不含 Pb、针铁矿和石英的处理相比，D. desulfuricans G20 在 5 天的滞后时间后生长，而在不含 Pb、针铁矿和石英的处理中则在 2 天内生长。然而，在没有针铁矿和石英的情况下，尽管存在 26 μM 可溶性 Pb，但没有观察到可测量的生长。结果表明，D. desulfuricans G20 首先从溶液中去除 Pb，然后开始生长，导致 Pb 和铁硫化物的黑色沉淀。用 10 μM PbCl(2)在不含针铁矿和石英的处理中处理 D. desulfuricans G20 的薄切片的透射电子显微镜分析显示，在外周质和细胞质中都存在密集的 Pb 硫化物沉淀。然而，用针铁矿、石英和 PbCl(2)（26 μM 可溶性 Pb）处理的 D. desulfuricans G20 的薄切片显示，在外周质和细胞质中都存在密集的铁硫化物沉淀。能量色散 X 射线光谱、选区电子衍射图谱或 X 射线衍射分析证实，在不含针铁矿和石英的处理中，细胞内沉淀的 Pb 的结构为方铅矿（PbS），而在含有针铁矿、石英和 PbCl(2)的处理中则为铁硫化物。总体结果表明，即使在相同的可溶性 Pb 浓度（26 μM）下，在存在针铁矿和石英的情况下，D. desulfuricans G20 对 Pb 的明显毒性显著降低。此外，Pb/铁硫化物在 D. desulfuricans G20 细胞内的积累取决于针铁矿和石英的存在。
