Environmental controls on microbialite and microbial mat biomineralization in Saskatchewan

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Mineral biosignatures and microbial communities: Mineral biosignatures are sediments or rocks with structures uniquely produced by living organisms. When identified in the rock record, mineral biosignatures provide a record of historical microbial life; for example, helical threads of rusty minerals are evidence of bacterial activity in iron-rich waters. Geologists use this information to help understand the history of ancient environments and life on Earth. Saskatchewan's prairie landscape hosts a range of unique environments where microbes produce mineral biosignatures, including iron and sulfur microbial mats in mineral springs and marshes. In prairie saline lakes, microbes can accelerate biomineral formation and accumulate in microbialites (layered mound structures). These biological systems experience dramatic seasonal extremes of temperature and aridity in Saskatchewan's continental climate. Changing climate conditions concomitant with global climate change contribute additional stresses and affects of these changes on mineral biosignatures has not yet been documented. Objective: The objective of this research program is to determine how changing climate parameters (e.g., temperature, salinity) affect microbial communities in microbialites and microbial mats, and how this influences mineral biosignature formation, alteration, morphology, and geochemistry. Scientific approach: This research will integrate a multidisciplinary suite of field and laboratory research methods. We will use molecular microbiological techniques to study diversity, distribution, and seasonal microbiological variations at our field sites and microbes from these environments will be cultured and characterized. Light and electron microscopy and synchrotron-based analytical tools will be used to examine the mineral structures, morphology, and chemistry of the biosignatures. Lab-based model systems will simulate environments where these biosignatures form and test the influence of changing conditions on biosignature formation. Impact: Examining the geomicrobiology of modern biosignature environments in Saskatchewan will produce original research with implications for understanding microbe-mineral interactions in these systems globally and in geological history, as well as in industry-relevant applications. This research will illuminate relationships between seasonal changes, climate change, and mineral biosignature formation and alteration that will improve our ability to recognize and interpret biosignatures in the rock record, and in extraterrestrial environments such as Mars. The microbes we isolate will have value as model organisms for research, and in water treatment applications (e.g., removal of iron or sulfur from groundwater). Broader scientific impacts include new insight on how changing climate parameters influence similar microbe-mineral interactions in other settings (e.g., in corrosion of steel infrastructure, in mine wastes, and in sediments and soils).