Atomic force microscopy image of biosurfactant -Cu2
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Atomic force microscopy image of biosurfactant -Cu2+ organized assemblies

May 26, 2010
Atomic force microscopy image of biosurfactant -Cu2+ organized assemblies spontaneously absorbed on graphite surfaces intended to model soil organic matter. [Image 2 of 2 related images. See Image 1.]

Surfactants--or surface-active agents--are substances that lower the surface tension, forming a membrane-like barrier between different liquid phases that affects the ability of molecules to move from one phase to another. In addition to synthetically produced surfactants, these substances are also produced by a wide diversity of microorganisms. Some types of "biosurfactants" can bind tightly to toxic metals, such as lead and cadmium, while others can adhere strongly to surfaces, sometimes completely changing the properties of the surface. Researchers want to know how biosurfactant production in soil systems influences the behavior of toxic metal contaminants. To answer this question, a microbiologist, a surface chemist and an expert in NMR spectroscopy are working together to discover (1) how much of the class of biosurfactants known as rhamnolipids are produced in soil; (2) how these rhamnolipids complex toxic metals such as lead and cadmium; and (3) how these biosurfactants interact with soil surfaces in the presence and absence of metals. This information is a critical piece of the puzzle required for understanding how metals are mobilized and immobilized under both natural and engineered conditions.

This research is supported by a grant from the National Science Foundation (CHE 01-33237), awarded to Raina M. Maier and Jeanne E. Pemberton, University of Arizona, and Cynthia K. Larive, University of Kansas. (Year of image: 2003)

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