Accumulation of Heavy Metals by Individually Analyzed Bacterial Cells and Associated Nonliving Material in Polluted Lake Sediments
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- 作者：Togwell A. Jackson ; M. Marcia West ; and Gary G. Leppard
- 刊名：Environmental Science & Technology
- 出版年：1999
- 出版时间：November 1, 1999
- 年：1999
- 卷：33
- 期：21
- 页码：3795 - 3801
- 全文大小：212K
- 年卷期：v.33,no.21(November 1, 1999)
- ISSN：1520-5851
文摘
The microfloras of sediments control the biogeochemicalcycling of heavy metals in natural waters, thereby determining,in large part, the ecological effects of the metals. However,little is known about interactions of metals with individualbenthic microbes in nature owing to the technical difficultyof studying such small-scale processes in complex,heterogeneous sedimentary ecosystems. Seeking to overcomethis obstacle, we used energy-dispersive X-ray microanalysisand transmission electron microscopy to investigatethe accumulation of Cu and other elements by the cellwalls, cytoplasm, cytoplasmic inclusions, fibrils, and mineralcoatings of individual bacterial cells in the sediments ofa lake polluted with heavy metals. Data from statisticallymeaningful numbers of specimens revealed variousassociations of elements with each other and with specificmicrostructures. The results imply (i) common occurrenceof Fe and Mn oxyhydroxide coatings on cell walls andfibrils; (ii) strong sorption of Cu by these coatings and theinability of Ca, Mg, and K to displace the Cu from thebinding sites; (iii) weaker but more extensive direct sorptionof Cu by cell walls from which the Cu is readily displacedby Ca, Mg, and K; (iv) blockage of cell wall ligands bySi-, Al-, and Fe-bearing mineral deposits; and (v) preferentialaccumulation of Cu in the coatings or in cytoplasmicinclusions enriched in Fe and usually enriched in P aswell (with or without measurable enrichment in Mn) withrespect to the cytoplasm. Our findings help to elucidate theaccumulation of heavy metals by microbes in aquaticecosystems and suggest the existence of diverse mechanismsof detoxification.