Wednesday, November 7, 2007
292-4
Molecular Analysis of Denitrifying Bacterial Populations in Soils of the Lower Mississippi River Valley: Impact of Land Use.
Hee-Sung Bae1, Stephen P. Faulkner2, Josh Mire1, and Aixin Hou3. (1) Louisiana State University, 3145 ECE Bldg Depart Environ Studies, Department of Environmental Studies, Baton Rouge, LA 70803, (2) USGS National Wetlands Research Center, 700 Cajundome Blvd., Lafayette, LA 70806, (3) Louisiana State University - Agronomy & Environmental Management, Louisiana State University, Dept. of Environmental Studies, Baton Rouge, LA 70803
During the last 200 years over 75% of the original riparian forests of the Lower Mississippi Valley has been converted to other land uses, mainly agriculture. This conversion has radically changed the biogeochemical functionality of the altered ecosystems, in particular their ability to retain and process N. This study focused on assessment of land use impact on denitrifying bacterial populations that play an important role in removing nitrogen from the Lower Mississippi River Valley. The population size of denitrifying bacteria was quantified via real-time PCR technique using two primer systems that targeted nitrite reductase gene (nirK) and nitrous oxide reductase gene (nosZ), respectively. Soil samples were collected from three different sites, namely forested wetland (FR), cultivated agricultural land (AG), and restored conservation reserve site (SBR). The copy number of nirK ranged from 1.5 x 106 to 3.0 x 106 per gram dry soil, while the gene copy number of nosZ ranged from 4.3 x 106 to 8.0 x 106 per gram dry soil. There were no order of magnitude differences observed among different land use sites. Subsequent study was carried out to assess the diversity of genes nirK and nosZ in these soil samples.