N-207. Diversity of Methanogens and Sulfur-Reducers in the Sediments of a Constructed Wetland in Monterey County, CA

P. Matheus-Carnevali, S. Rech;
San Jose State Univ., San Jose, CA.

Methane may have played a critical role in the chemistry of the early atmosphere and it is the focus of many current studies. Methanogenesis, carried out only by members of the domain Archaea, is the main source of the natural methane today. Archaea thrive in the sediments of wetland ponds where they compete for methanogenic substrates with sulfur-reducing bacteria (SRB). The purpose of our study is to determine the diversity of methanogens and SRB in the sediments of a constructed wetland in Monterrey County, CA, and to monitor changes in these populations along a nutrient gradient. Sediment samples were collected on July 2007 at four different sites along the gradient, using a 5x10 cm core device. Community genomic DNA was extracted by using a MoBio kit. Our PCR-based approach relies on the 16S rRNA gene to survey general Bacteria and Archaea diversities, with the creation of clone libraries in order to obtain representative sequences from both divisions. 34 clones of Bacteria have been obtained only from the first site. Archaea clones library is being created. The next stage involves nested-PCR using group specific primers for the 16S rRNA gene of methanogens and SRB. The fragments amplified will be analyzed by DGGE to illustrate diversity and isolate fragments for sequencing. Finally, phylogenetic trees will be used to characterize the microbial populations.