Assessment of Microbial Community Structure and Function within Two Oligotrophic Peatlands.

Soil microbial communities are highly complex and interactive networks that drive many biogeochemical processes.  In this study, we apply a combination of bioinformatics techniques with molecular data to begin to understand the structure of these communities and how they may be functioning with respect to nutrient cycling.  We used two oligotrophic peatlands as our study sites: the Everglades of South Florida and San San Pond Sak of Panama.  Both sites are characterized by well-studied phosphorus (P) gradients, that have led to documented changes in plant communities and biogeochemical cycling.  Our objectives for this study were to first create putative phylogenetic networks for microbial groups along each gradient, and secondly to determine how nutrient availability along the gradients influenced microbial P and nitrogen (N) cycling genes. We sampled soils at sites spanning both gradients, from low-P to high-P sites, isolated DNA from these soils, and used 16S rRNA metagenomic techniques to assess prokaryotic community structure and quantitiative PCR to determine the relative abundance of key P and N cycling genes.  We found that putative networks shifted along both gradients, and that the ratio of gene abundances, particularly those of alkaline phosphatase (phoX and phoD) and dinitrogenase reductase (nifH), were found to be consistent with the shifts in nutrient limitation, and appear to agree with enzyme assays conducted at the same sites.  By studying the dynamics of microbial community structure and function within oligotrophic peatlands, such as the Everglades and San San Pond Sak, we can better understand the interlinked dynamics of microbial nutrient cycling in these unique systems.