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Tracing Microbes using Phosphate in Fe-oxide Environments

Final Report Summary - TMUPIFE (Tracing Microbes using Phosphate in Fe-oxide Environments)

Biomineralization is a critical skill utilized by many different biological systems. The minerals made by these biological processes can be distinctly different from those of abiotic systems, thus understanding how biology can modify biomineralization processes can help us to design novel materials, provide diagnosis and treatment options for some diseases and help find clues in the hunt for life on different planets. During the course of this project the researcher, Dr. King, has focused on two main aspects of biomineralization. The first examines use of isotopic signatures locked into Fe(III)-oxides produced by bacteria. On Earth Fe(II)-oxidizing microbes are deep-branching and hence ancient life forms. In modern times these microbes can be found in a wide variety of different environments including freshwater, saline and acidic as well as oxic and anoxic conditions. Other planets, such as Mars, are also expected to have significant iron that could act as a potential energy source for similar types of bacteria, therefore understanding whether minerals associated with microbial Fe(II)-oxidation can retain a biosignature will provide us with a target in the hunt for life in extraterrestrial environments. As part of this aim Dr. King developed skills in microbiology during the course of this project to study biomineralization related to microbial Fe(II) oxidation in both acidic and neutral pH environments. In addition she has examined natural biological signatures of Fe(II)-oxidizing microbial mats obtained during the 2014 Nautilus expedition using the analysis of 18-O isotopic signatures. This work was expanded upon during the return phase of the project, at Utrecht University, where Dr. King has set up a collaboration with the microbiology lab of Deltares to grow Fe(II)-oxidizing bacteria, successfully transferring these skills to Utrecht University. Dr. King has also incorporated the use of the state-of-the-art nanoscale secondary ion mass spectrometry (nanoSIMS) facility available at Utrecht University for this research. The results of these studies have led to at least one publication, currently being written up, as well as ongoing applications for funding for future collaborative research between Dr. King and Prof. Blake. Dr. King is also in contact with consultants related to the mining industry to discuss the results of this study as it may be interesting for biomining projects, where Fe(II)-oxidizing bacteria are used to leach valuable metals from mine tailings.
In addition to the microbial work, during her time at Yale University Dr. King was also approached by Dr. Skinner, a bone mineralization specialist, within the Department of Geology and Geophysics for help with an ongoing project related to bone mineralization. This project utilized Dr. King’s previous knowledge of spectroscopy to examine changes in the mineral components of bone between healthy mice and mice with a genetic condition which prevents adequate uptake of Ca and phosphate from their diet. The results of this work, one article has been accepted for publication and a second is currently in review, demonstrate that bone mineralogy varies depending on the extent of bone remodelling and the ability of the animal to provide enough Ca and phosphate to the mineral growth sites. The results of this study were presented at the Goldschmidt 2015 geochemistry conference in Prague. As for the microbial biomineralization work, this project has led to applications for further funding as an ongoing collaboration between Dr. King and Dr. Skinner as well as Dr. Tommasini, part of the Yale Medical School. This project has direct societal relevance as it uses a murine model of the human genetic disorder X-linked hypophosphatemia and alternative bone remodelling mechanisms active in hypophosphatemia patients may also be important for osteoporosis research.