| Extracellular Polymeric Substances from Bacillus subtilis Associated with Minerals Modify the Extent and Rate of Heavy Metal Sorption. | |
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MedLine Citation:
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PMID: 22443088 Owner: NLM Status: Publisher |
Abstract/OtherAbstract:
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Extracellular polymeric substances (EPS) are an important source of organic matter in soil. Once released by microorganisms, a portion may be sorbed to mineral surfaces, thereby altering the mineral̀s ability to immobilize heavy metals. EPS from Bacillus subtilis were reacted with Ca-saturated bentonite and ferrihydrite in 0.01 M KCl at pH 5.0 to follow the preferential uptake of EPS-C, -N, and -P. The sorption kinetics of Pb(2+), Cu(2+), and Zn(2+) to the resulting EPS-mineral composites was studied in single and binary metal batch experiments ([metal](total) = 50 μM, pH 5.0). Bentonite sorbed much more EPS-C (18.5 mg g(-1)) than ferrihydrite (7.9 mg g(-1)). During sorption, EPS were chemically and size fractionated with bentonite favoring the uptake of low-molecular weight components and EPS-N, and ferrihydrite selectively retaining high-molecular weight and P-rich components. Surface area and pore size measurements by N(2) gas adsorption at 77 K indicated that EPS altered the structure of mineral-EPS associations by inducing partial disaggregation of bentonite and aggregation of ferrihydrite. Whereas mineral-bound EPS increased the extent and rate of Pb(2+), Cu(2+), and Zn(2+) sorption for bentonite, either no effect or a decrease in metal uptake was observed for ferrihydrite. The extent of sorption always followed the order Pb(2+) > Cu(2+) > Zn(2+), which also prevailed in binary Pb(2+)/Cu(2+) systems. In consequence, sorption of EPS to different minerals may have contrasting consequences for the immobilization of heavy metals in natural environments by inducing mineral-specific alterations of the pore size distribution and, thus, of available sorption sites. |
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Authors:
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Robert Mikutta; Anja Baumgärtner; Axel Schippers; Ludwig Haumaier; Georg Guggenberger |
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Publication Detail:
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Type: JOURNAL ARTICLE Date: 2012-3-23 |
Journal Detail:
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Title: Environmental science & technology Volume: - ISSN: 1520-5851 ISO Abbreviation: - Publication Date: 2012 Mar |
Date Detail:
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Created Date: 2012-3-26 Completed Date: - Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 0213155 Medline TA: Environ Sci Technol Country: - |
Other Details:
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Languages: ENG Pagination: - Citation Subset: - |
Affiliation:
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Institut für Bodenkunde, Leibniz Universität Hannover , Germany. |
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From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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