NIRT: Nanoscale Processes in the Environment: Nanobiogeochemistry of Microbe/Mineral Interactions

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EAR-0103053HochellaThe primary objective of this research program is to observe and quantitatively characterize, on the nanometer (10-9 meters) scale, the complex interactions that occur between microorganisms (specifically bacteria) and minerals. These interactions are ubiquitous in soils and rocks near the Earth's surface. We hypothesize that microbe-mineral interactions, when studied directly at the nanoscale, will result in the discovery of exotic behavior relative to current concepts and models that seek to explain mineral-microbe association and dependence. In order to accomplish our goal, we will depend heavily on biological force microscopy (BFM), a variation of the atomic force microscope that we have developed in our lab over the last two years. This technique, for the first time, allows for the direct measurement of forces (both attractive/repulsive and adhesive) between fully functional cells and any other substrate as a function of separation distance. Reproducible and reliable measurements between bacteria and mineral surfaces are readily obtained with nano- to pico (10-12)-Newton force resolution while at the same time controlling their separation to the nanometer level. This has already given us an unprecedented view of the intricacies on mineral-microbe interaction as a function of water chemistry, microbial physiology, and surface mineralogy. Practical application of this work includes the development of a new generation of transport model for microorganisms in surface or subsurface environments, using the wealth of nanoscale information obtained from our BFM and associated measurements. Such models should be very useful in developing more robust subsurface bioremediation strategies in the future. This proposal was submitted in response to the solicitation "Nanoscale Science and Engineering" (NSF 00-119).