Abstract
To understand patterns of geochemical cycling in pristine versus contaminated groundwater ecosystems, pristine shallow groundwater (FW301) and contaminated groundwater (FW106) samples from the Oak Ridge Integrated Field Research Center (OR-IFRC) were sequenced and compared to each other to determine phylogenetic and metabolic difference between the communities. Proteobacteria (e.g., Burkholderia, Pseudomonas) are the most abundant lineages in the pristine community, though a significant proportion ( >55%) of the community is composed of poorly characterized low abundance (individually <1%) lineages. The phylogenetic diversity of the pristine community contributed to a broader diversity of metabolic networks than the contaminated community. In addition, the pristine community encodes redundant and mostly complete geochemical cycles distributed over multiple lineages and appears capable of a wide range of metabolic activities. In contrast, many geochemical cycles in the contaminated community appear truncated or minimized due to decreased biodiversity and dominance by Rhodanobacter populations capable of surviving the combination of stresses at the site. These results indicate that the pristine site contains more robust and encodes more functional redundancy than the stressed community, which contributes to more efficient nutrient cycling and adaptability than the stressed community.
Highlights
About one third of global freshwater reserves are located in subsurface streams and aquifers and represent a critical source of fresh water for human consumption and irrigation (Gleick, 2000)
The objectives of this study were to pursue the following questions: (i) What is the phylogenetic and functional diversity of pristine and how does it compare to the stressed groundwater community? (ii) How robust is the pristine community to environmental perturbation? (iii) How does a microbial community adapt to severe environmental changes such as heavy metal contamination? To address the above questions, the pristine metagenome was characterized and compared to the re-sequenced contaminated metagenome of the contaminated groundwater microbial community
The results suggest that the pristine groundwater community is highly diverse and encodes a high degree of metabolic potential and functional redundancy
Summary
About one third of global freshwater reserves are located in subsurface streams and aquifers and represent a critical source of fresh water for human consumption and irrigation (Gleick, 2000). Significant portions of natural groundwater reserves are rendered unusable due to anthropogenic contaminations that results from by-products of industry, agricultural runoff, and human/animal waste (Kunin et al, 2008). Environmental contaminants affect the quality of groundwater directly and alter various biogeochemical cycling processes by altering native microbial communities. The loss of biodiversity in groundwater communities as a result of contamination greatly impacts geochemical cycling within the groundwater ecosystem (Cardenas et al, 2008; Moreels et al, 2008). Understanding the nature of stress response and geochemical cycling in contaminated groundwater communities is critical for the design of effective in situ restoration strategies to rehabilitate and protect groundwater
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
