Development and application of functional gene profiling and quantification of microbial communities remediating mine drainage.

摘要

Mine drainage (MD) is the product of the oxidation of sulfide minerals. It is characterized by elevated concentrations of heavy metals and sulfate and acidic to near-neutral pH. Sulfate-reducing permeable reactive zones (SR-PRZs) represent a common passive treatment approach for MD. Although SR-PRZs are microbially catalyzed, little is known about their microbiology and ecology. In this research, several aspects of the SR-PRZ microbial community were explored at laboratory and pilot scales with established as well as newly developed biomolecular methods.;A study using microcosm column experiments demonstrated that the type of inoculum plays an important role in the bioremediation of MD. The effect of the type of substrate on the microbial community was also investigated in pilot-scale SR-PRZs treating the MD. Lignocellulose-based SR-PRZs contained a more diverse microbial community and higher bacterial density than ethanol-fed SR-PRZs, as determined by 16S rRNA gene cloning and quantitative polymerase chain reaction (Q-PCR).;A new biomolecular approach was developed to target genetic markers of the functions of interest (functional genes): cellulose degradation, fermentation, sulfate reduction, and methanogenesis. This approach provided a more efficient and direct means of studying microbial functions. The functional gene-based approach was adapted to denaturing gradient gel electrophoresis and Q-PCR and applied to study the microbial communities in laboratory columns simulating SR-PRZs during the initial and pseudo-steady-state operation. Although the microbial communities in the different treatments were different during pseudo-steady-state operation, performance of the columns was comparable in terms of sulfate and metal removal and pH neutralization. This suggests that various microbial compositions can lead to successful MD remediation.;The studies presented in this dissertation provide significant insight in the microbial communities involved in MD remediation at laboratory and pilot scale. In addition, a variety of biomolecular methods are presented that can be applied to explore different aspects of the microbial community not only in SR-PRZs and but also in other systems with complex microbial communities. Integration of biomolecular and performance data will provide a more complete understanding of SR-PRZ function that could be used to improve SR-PRZ performance and reliability.