The effect of long-term mixed-waste contamination, particularly uranium and nitrate, on the microbial community in the terrestrial subsurface at the Oak Ridge Integrated Field Research Challenge (ORIFRC) site in Oak Ridge, TN has been extensively characterized to determine appropriate remediation strategies. In this talk, I will review combined cultivation-based and cultivation-independent molecular analyses used to understand the composition of microbial communities across a contamination gradient at the ORIFRC site. Key findings of these studies include the highly abundant presence of active, denitrifying bacteria from the genus Rhodanobacter at the contamination source zone and the presence of denitrifying fungi at lower levels. The genomics and physiology of Rhodanobacter isolates are explored to understand the physiological mechanisms by which these organisms achieve their dominance in the source zone. In addition, I examine the critical role of methodology in microbial community analyses and highlight the importance of combined cultivation-based and cultivation-independent methodologies for characterizing the microbial ecology of environmental systems.

Learning Objectives:

1. Review the critical role for cultivation in understanding cultivation-independent sequence data.

2. Discuss genomic capabilities of microorganisms tolerating a highly contaminated subsurface environment.

3. Summarize the ecological niche for bacteria from the genus Rhodanobacter.