Environmental contaminants, such as soluble metal ions and agricultural wastes pose great risks for both human health and ecosystems. To reduce these risks, environmental engineers have developed remediation approaches that take the advantage of microbial communities and populations. Understanding these microbial resources is instrumental to manage and apply them in various engineered systems. In this dissertation, I study microbial communities and populations from three different approaches and demonstrate how basic microbial information can assist us in optimizing engineered systems. The first part of my dissertation focuses on understanding the genomic advantages of Ralstonia pickettii strains, which allows them to adapt to high copper environments. We have previously shown that these two strains were able to sequester a large amount of copper. Hence, these two bacterial strains have a great potential in for application to industrial wastewater treatment. Understanding the genomic evolution and adaptation behind the copper binding phenomenon could unveil the industrial potential of these bacterial strains. The second part of this dissertation focuses on understanding the role of anaerobic bacterial populations and communities in uranium immobilization. A large amount of research has been conducted on identifying the bacterial communities involved in in situ uranium immobilization. However, the extant of soil microbial diversity made it difficult to identify the most important specific populations. We employed enrichment culture methods to increase the abundance of potential important bacterial populations and to link the community functions. Finally, I present a study on microbial communities in methane producing agricultural waste co-bioreactors. Methane production has been reported as a highly cooperative reaction between bacteria and archaea. Linking bacterial populations to specific functions would help optimize agricultural waste degradation as well as alternative energy production. I chose these three topics to emphasize the importance of microbial populations in engineered systems. By understanding the roles of individual bacteria populations as well as their interactions with each other in a community, I hope to manage and utilize these microbial resources to improve our living environment.
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