Sorption versus Biomineralization of Pb(II) within Burkholderia cepacia Biofilms

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• 作者：Alexis S. Templeton ; Thomas P. Trainor ; Alfred M. Spormann ; Mathew Newville ; Steven R. Sutton ; Alice Dohnalkova ; Yuri Gorby ; and Gordon E. Brown ; Jr.
• 刊名：Environmental Science & Technology
• 出版年：2003
• 出版时间：January 15, 2003
• 年：2003
• 卷：37
• 期：2
• 页码：300 - 307
• 全文大小：381K
• 年卷期：v.37,no.2(January 15, 2003)
• ISSN：1520-5851

文摘

X-ray spectroscopy measurements have been combinedwith macroscopic uptake data and transmission electronmicroscopy (TEM) results to show that Pb(II) uptake byBurkholderia cepacia is due to simultaneous sorption andbiomineralization processes. X-ray microprobe mappingof B. cepacia biofilms formed on -Al₂O₃ surfaces showsthat Pb(II) is distributed heterogeneously throughout thebiofilms because of the formation of Pb "hot spots". EXAFSdata and TEM observations show that the enhanced Pbaccumulation is due to the formation of nanoscale crystalsof pyromorphite (Pb₅(PO₄)₃(OH)) adjacent to the outer-membrane of a fraction of the total population of B. cepaciacells. In contrast, B. cepacia cell suspensions or biofilmsthat were heat-killed or pretreated with X-rays do notform pyromorphite, which suggests that metabolic activityis required. Precipitation of pyromorphite occurs overseveral orders of magnitude in [H⁺] and [Pb] and accountsfor approximately 90% of the total Pb uptake below pH4.5 but only 45-60% at near-neutral pH because of theformation of additional Pb(II) adsorption complexes. Structuralfits of Pb L_III EXAFS data collected for heat-treated cellsat near-neutral pH suggest that Pb(II) forms inner-sphereadsorption complexes with carboxyl functional groups inthe biofilms.