Contaminant stress on ecosystems: investigating microbial redox transformations of metal(loids) and novel tracers

矿物和微生物之间的相互作用对水-岩系统中溶解的金属和类金属离子的运输和毒性的影响以及它们对风化和矿物形成的控制，使矿物和微生物之间的相互作用受到基本和日益增长的关注。调节环境中金属的质量运输、转化和毒性的微生物过程是复杂的。金属和类金属可以在其环境中被微生物以酶或非酶的方式浓缩和分散。例如，我们实验室的研究表明，在细菌存在下形成的金属/液体可以在不断变化的氧化还原环境中发生剧烈的转化和物种形成。当然，这些差异可能取决于存在的细菌种类，由于物种之间细胞壁结构的差异而促进模板效应。即使在单一物种中，变化也会导致代谢状态或生长过程中产生的渗出物（细胞外聚合物，EPS）的浓度和类型的变化，这些变化会影响生物矿物质的性质，从而可能影响它们在周围介质中的吸附能力。该研究项目将重点关注受细菌还原和氧化形式影响的关键矿物系统（例如，硫酸铁类似物，如黄钾铁矾末端成员矿物）。实验将使用纯培养物和微生物群落（从沉积物和土壤中的铁还原区分离出来）。天然硫酸铁，包括那些形成于酸性硫酸盐土壤系统和合成的端元将用于控制实验室实验。此外，该计划的研究还将侧重于开发新的环境示踪剂，以表征人为影响。维持可持续的淡水资源直接关系到加拿大持续的社会经济成功（即农业、工业、人口和旅游业）。加拿大的矿产和能源工业正处于过去三十年来最大的扩张时期。这个研究项目将加强我们对细菌如何控制自然生态系统中金属释放的理解，以及那些受采矿部门和人为投入影响的生态系统。

Interactions between minerals and microorganisms are of fundamental and growing interest due to their influence on the transport and toxicity of dissolved metal and metalloid ions in water-rock systems and their control on weathering and formation of minerals. The microbial processes that regulate the mass transport, transformations, and toxicity of metals in the environment are complex. Metals and metalloids can be enzymatically or non-enzymatically concentrated and dispersed by microbes in their environment. For example, studies in our lab have shown that metal/loids formed in the presence of bacteria can undergo dramatic transformation and speciation in changing redox environments. These differences of course, can depend on the bacterial species present, promoting template effects due to differences in cell wall structure between species. Even in single species, variations can result in metabolic state or the concentration and type of exudates (extracellular polymeric substance, EPS) produced during growth can affect the properties of the bio-minerals and thereby potentially influence their adsorptive capacity within the surrounding media. This research program will focus on key mineral systems (e.g. iron sulphate analogues such a jarosite end member minerals) influenced by reducing and oxidizing forms of bacteria. Experiments will use pure cultures and microbial consortia (isolated from iron reducing zones in sediments and soils). Natural iron sulphates including those formed in acid sulphate soil systems and synthesized end-members will be used in controlled laboratory experiments. In addition research within this program will also focus on developing new environmental tracers to characterize anthropogenic influences. Maintaining sustainable freshwater resources are directly tied to Canada's continued socio-economic success (i.e. agriculture, industry, people, and tourism). The minerals and energy industries in Canada are in the midst of their greatest expansion in the last three decades. This research program will enhance our understanding of how bacteria control metal release in natural ecosystems as well as those impacted by mining sector and anthropogenic inputs.