Microbial community analysis of Bisley watershed in Puerto Rico

Project Description: 

Biological processes are known to play significant roles in soil formation and surficial weathering. However, the contributions of biological activity to regolith and rock weathering below the root zone are less well understood, especially in humid tropic forests that have shallow root systems and rapid nutrient cycling in surficial layers. In Puerto Rico, thick, highly leached saprolites blanket the landscape, reaching well over 16 m deep on some ridges, often decoupling deep biogeochemical cycles from surface cycles. Surface ecosystems tightly recycle nutrients in tropical forests, leaving little to infiltrate to deeper communities. Thus, deep microbial ecosystems are highly dependent on bedrock weathering processes for nutrients.

In a previous study, the microbial content of deep regolith (soil+saprolite) cores in the Rio Icacos watershed was examined and a relationship was established in which microbial oxidation of iron supplied by bedrock weathering at depth supported the deep microbial community. Ongoing work is focusing on regolith cores collected in the Bisley watershed to look at the effect of lithology on microbial patterns. Analytical work includes plate counts, biochemical tests for iron-oxidizing and -reducing bacteria, and a suite of molecular biological analyses including DNA extraction, PCR, and genomic analyses.

Research Location: 
Source of Funding: 
LCZO and Department of Energy grant number DE-FG02-05ER15675 (to Brantley)
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Contact Information
Person(s) Completing This Form: 
Heather L. Buss
Laura Liermann (ljl8@psu.edu), Penn State University, University Park, PA Susan L. Brantley (Brantley@eesi.psu.edu), Penn State University, University Park, PA Heather L. Buss (hlbuss@usgs.gov), U.S. Geological Survey, Menlo Park, CA
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