Deciphering the structure and chemistry of microbial mat-fluid-mineral interactions in three-dimensions for application to environmental challenges

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Microbes can endure extremes in temperature, acidity, and high concentrations of dissolved metals. These organisms often grow as microbial mats, which are layered structures found at surface-fluid boundaries. Microbial mats host microbes exhibiting various metabolic pathways, some of which can precipitate or dissolve economically or environmentally important minerals. This capacity to facilitate geochemical reactions means that microbial mats can be thought of as naturally occurring bioreactors that have impacted the environment throughout the history of life on Earth. The proposed research aims to develop a geomicrobiological `toolbox' of characterization and remediation strategies for application to natural environments and industrial scenarios. This will be targeted through three objectives: 1) resolving microbial mat structure and chemistry in three-dimensions, 2) temporally constraining microbial biomineralization processes, and 3) applying biomineralization to environmental challenges. Cyanobacteria dominated mats and microbialites collected from lakes in the Cariboo Plateau region in British Columbia will be the primary target specimens. These sites are among the best examples of modern stromatolite formation in Canada and host microbial communities suitable for the proposed carbonation and metal reactivity experiments. The proposed research will improve our ability to observe microbial mat structure and chemistry, a result that will have impact across the field of Geomicrobiology. These developments will aid characterization of microbial carbonate mineral nucleation reactions studied in relation to fluid chemistry and microbial activity. Structural and spectral analyses of organic matter preserved in stromatolite microfossils will yield a contemporary example of biosignature preservation in carbonate mineral phases. The ability of microbes to bind metals will be studied in metal exposure experiments. Changes in exopolymer production and cyanobacteria photosynthetic activity in response to metal exposure will reveal how these organisms tolerate metals while immobilizing them from solution. These outcomes will be combined with the carbonate precipitation experiment results by testing the potential for metals to be immobilized in biogenic carbonate minerals. The aim is to develop a biogeochemical process by which toxic metals and atmospheric carbon can be co-sequestered in benign carbonate phases. Developing paired carbon sequestration and metal remediation for deployment at mine tailing storage facilities will aid mine site remediation across Canada and is a long term goal of this research program. The program will succeed through the efforts of highly qualified students who will gain experience in analytical techniques, experiment design, critical thinking, and communication. Students will become assets in the employment avenues they chose to pursue across academic, industrial, and government sectors.