Collaborative Research: Interactions of Heavy Metals With Biofilm-Coated Mineral Surfaces

Traina 9910569微生物生物膜是许多环境中矿物表面的常见涂层，已知可吸附金属离子，如Pb（II）。然而，目前对这些金属离子在分子水平上的化学形式、它们在生物膜中的空间分布以及生物膜影响金属离子在矿物表面吸附的机制知之甚少。这个多学科的项目将通过实验室研究铅（II）吸附生物膜涂层表面的铝和铁（氢）氧化物和石英作为几个解决方案变量的函数，解决这些问题和相关问题。Pb（II）在这些表面上生长的生物膜中的分子尺度形态和空间分布将使用基于同步加速器的X射线和电子显微镜方法进行研究。此外，我们将使用红外光谱法研究常见的无机配体PO 43-和几种有机配体对Pb（II）吸收的影响，这些配体是细菌表面和生物膜胞外多糖上的主要官能团。洋葱伯克霍尔德氏菌是一种需氧革兰氏阴性菌，在营养有限的条件下容易形成生物膜，被选为这项工作的初始阶段。我们的系统变量的选择将指导我们正在进行的铅污染的尾矿在Leadville，CO和土壤在北方法国的铅形态的研究结果。将探讨细胞外磷酸盐和细胞内的邻和多磷酸盐代谢的生物膜中产生的铅-磷酸盐的作用。我们的方法从相对简化的模型系统开始，系统地增加了一些自然系统的复杂性。这项工作的最终目标是对控制地球化学循环的一些因素有一个基本的了解该提案是应NSF 99-9环境地球化学和生物地球化学征集而提交的，并由化学、地球科学、海洋科学、地球物理和地球化学部联合资助。MPS多学科活动办公室

Traina9910569Microbial biofilms are common coatings on mineral surfaces in many environments and are known to sorb metal ions such as Pb(II). However, little is currently known about the chemical form(s) of these metal ions at a molecular level, their spatial distribution in the biofilm, and the mechanisms by which the biofilm affects metal ion sorption on mineral surfaces. This multidisciplinary project will address these and related issues through laboratory studies of Pb(II) sorption on biofilm-coated surfaces of aluminum and iron (hydr)oxides and quartz as a function of several solution variables. The molecular-scale speciation and spatial distribution of Pb(II) in biofilms grown on these surfaces will be studied using synchrotron-based x-ray and electron microscopy methods. In addition, we will use infrared spectroscopy to study the effects on Pb(II) uptake of the common inorganic ligand PO43- and several organic ligands that are dominant functional groups on bacterial surfaces and biofilm exopolysaccharides. Burkholderia cepacia, an aerobic gram-negative bacterium that readily forms biofilms under nutrient-limited conditions, was chosen for the initial phases of this work. Our choice of system variables will be guided by the results of our ongoing studies of Pb speciation in several Pb-contaminated tailings at Leadville, CO and soils in northern France. The role of extracellular phosphate and of intracellular ortho- and polyphosphate metabolism in the biofilm in producing Pb-phosphates will be explored. Our approach starts with relatively simplified model systems and systematically adds some of the complexities of natural systems. The ultimate goal of this work is to develop a fundamental understanding of some of the factors that control the geochemical cycling (and potential bioavailability) of Pb and other metals in aquatic environments.This proposal was submitted in response to the Environmental Geochemistry and Biogeochemistry solicitation NSF 99-9, and is being funded jointly by the Divisions of Chemistry, Earth Sciences, Ocean Sciences, and MPS Office of Multidisciplinary Activities.