METAL SEQUESTERING BY MICROORGANISMS IN AND FROM AQUATIC ENVIRONMENTS

本建议是2004年所作努力的扩大。 1992- 1993财政年度题为“痕量金属调查 被微微型浮游生物中的多磷酸盐体隔离。“我们现在将集中精力 微量金属和重金属被吸收的各种机制， 固定在自然界中发现的微生物群落中， 水生环境 我们的方法是利用 电子显微镜结合X射线能谱分析 (EDX)研究细菌大小的细胞及其相关的非细胞 微粒 这种定性和半定量的方法将使 我们分析细胞和细胞成分的元素含量， 使我们有可能定位金属离子成为 集中 我们一年来的学习和培训是卓有成效的 因为我们现在正在研究更复杂的自然水生生物， 系统. 我们将尝试分离出其他重要的数字， 金属固定化物质，并研究它们的金属吸收倾向。 我们将检查金属污染的水生沉积物中的细菌， 相关颗粒物，重要的重金属轴承活性污泥 并试图将积聚的金属定位在构成细胞的细胞中或细胞上， 生物质。 吸收并浓缩重金属的纯培养物 在机制研究方面具有很大的潜在价值，但它们也 可开发用于水净化、有价金属 回收或其他实际用途。 更重要的是， 从环境的角度来看，重金属可以被追踪到 从沉淀物中分离到细菌细胞团中。 许多 的细菌也可以作为食草原生动物的食物供应， 其他无脊椎动物。 我们在本提案中的努力将奠定 这类研究的基础。

The present proposal represents an expanded effort of that undertaken in the 1992-93 FY, which was entitled "Investigation of trace metal sequestering by polyphosphate bodies in picoplankton." We will now focus on the various mechanisms by which trace and heavy metals are taken up and immobilized within the microbial consortium that are found in the natural aquatic environments. Our approach will be to employ the transmission electron microscope in conjunction with X-ray energy dispersive analysis (EDX), to study bacterial-sized cells and their associated non-cellular particulates. This qualitative and semi-quantitative approach will enable us to analyze cells and cell constituents for their elemental content, and make it possible for us to localize regions in which metal ions become concentrated. Our study over the past year has been fruitful as training ground as we now undertake examination of more complex natural aquatic systems. We will attempt to isolate additional numerically important, metal immobilizing species and study their propensity for metal uptake. We will examine metal polluted aquatic sediments for bacteria and associated particulates, important heavy metal bearing activated sludge and attempt to localize accumulated metals in or on cells making up the biomass. Pure cultures that take up and concentrate a heavy metal have great potential value in the study of mechanisms involved but they also may be developed for use in aspects of water purification, valuable metal recovery or other practical uses. Of greater importance from an environmental standpoint is the fact that a heavy metal can be tracked from a sediment into a bacterial cell mass using the EM-EDX system. Many of the bacteria can also serve as a food supply for grazing protozoa and other invertebrate animals. Our effort in the present proposal will lay a groundwork for these kinds of studies.