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Microbial mineral colonization across a subsurface redox transition zone.
Brandon J Converse1, James P McKinley2, Charles T Resch2
1Department of Geoscience, University of Wisconsin-Madison Madison, WI, USA.
Frontiers in Microbiology
|September 18, 2015
Summary
Chemolithotrophic bacteria did not preferentially colonize biotite over quartz sand in a subsurface redox transition zone. Instead, heterotrophic bacteria dominated both mineral types, impacting elemental cycling and contaminant behavior.
Area of Science:
- Environmental microbiology
- Geomicrobiology
- Subsurface science
Background:
- Chemolithotrophic Fe(II)-oxidizing bacteria (FeOB) are known to inhabit Hanford 300 Area sediments.
- These bacteria can oxidize structural Fe(II) in silicate and phyllosilicate minerals.
- Understanding microbial colonization of minerals in redox transition zones is crucial for predicting biogeochemical processes.
Purpose of the Study:
- To test the hypothesis that FeOB preferentially colonize biotite over quartz sand.
- To investigate microbial community structure associated with mineral surfaces in a subsurface redox transition zone (RTZ).
- To assess the role of different mineral substrates in shaping microbial communities.
Main Methods:
- 16S rRNA gene amplicon pyrosequencing was used to analyze microbial communities.
- Sterilized sand+biotite and sand-only treatments were incubated in situ within an RTZ.
- Multilevel sampling (MLS) apparatus was deployed in groundwater wells for mineral incubation and geochemical measurements.
Main Results:
- No significant difference was observed in microbial communities colonizing sand+biotite versus sand-only.
- Both mineral-associated and groundwater communities were dominated by heterotrophic taxa, particularly Pseudomonadaceae.
- Putative lithotrophic taxa were detected, suggesting potential roles in biogeochemical cycling.
Conclusions:
- The hypothesis of preferential FeOB colonization of biotite was not supported.
- Heterotrophic bacteria play a dominant role in the Hanford 300 Area subsurface microbial communities.
- Detected lithotrophic bacteria may influence elemental cycling and contaminant behavior in the RTZ.
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