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Anne Anderson, Charles Miller and Joan McLean are all researchers at Utah State University. They interact together on this project as an interdisciplinary team where biological and engineering approaches are combined. Anderson and Miller are affiliated with the Department of Biology in the College of Science whereas Mclean is associated with the Department of Biological Engineering and Irrigation in the College of Engineering.
Anderson and Miller have backgrounds in plant-microbe interactions ranging from plant pathological systems to bioremediation. McLean has expertise in the chemistry of metals. This project was initiated through studies of the role of mechanisms in root-associated bacteria used for protection against oxidative stress. Mutants lacking key enzymes of oxidative stress were generated by the insertion of a luxAB cassette that would permit the transcription from the gene to be monitored by measurement of light emission. Because metals exert oxidative stress in cells, we predicted that measurement of light emission could serve to detect the presence of the metal. Our preliminary data confirmed this hypothesis but in spite of surveying three different promoter fusions (from genes encoding a major catalase, Fe-superoxide dismutase and a subunit for an iron binding bacterioferritin) there was little metal specificity in the responses. Thus, the goal became to generate more specific detectors for different toxic metals. The knowledge that plant roots secrete high levels of organic molecules that chelate metals spurred interest as to whether the biosensors can be used to answer questions of how different metal chelates are sensed by microbes. Consequently we are examining how biosensors for different metals can be constructed and how microbes respond to different chelates.